bluuebunny/crossref_metadata_2025 huggingface dataset:
ELECTROPHORETIC ANALYSIS OF ENZYMES FROM THREE SPECIES OF CHLAMYDOMONAS
Authors: Thomas Dempsey L. , Delcarpio Joseph B.
Published: January 2018

Isoenzyme patterns of acetone‐extracted proteins revealed a close similarity between Chlamydomonas eugametos and C. moewusii but a distant relationship between the two and C. reinhardtii. Chlamydomonas eugametos and C. moewusii had identical banding patterns of malate dehydrogenase (MDH) and leucine aminopeptidase (LAP) in starch gels. These two species exhibited the same MDH distribution spectrum in analytical disc polyacrylamide gels but neither species showed definitive LAP or glutamate dehydrogenase (GDH) activity. There were differences in the starch gel alpha esterase (α‐EST) patterns of C. eugametos and C. moewusii due to an additional weak band at Rf 0.75 in the latter species and a slight variation in the position of another band at Rf 0.80–0.82. Some variations between the two species also occurred in the α‐EST banding in disc gels at Rf 0.70–0.85 and at Rf 0.06–0.14 with C. moewusii exhibiting the greatest number of bands. Chlamydomonas reinhardtii displayed patterns of all four enzymes but the band characteristics were distinctively different from those of C. eugametos and C. moewusii. There appeared to be no obvious isoenzyme difference between mating types of either species. It is concluded that C. eugametos and C. moewusii are not identical species but are closely related in regard to the enzymes assayed. Isoenzyme analysis is considered to be a useful approach to algal systematics.
THE BIOLOGY OF THE EPIPHYTIC BROMELIAD TILLANDSIA CIRCINATA SCHLECHT. I. THE NUTRIENT STATUS OF POPULATIONS IN SOUTH FLORIDA
Authors: Benzing D. H. , Renfrow A.
Published: January 2018

The atmospheric epiphyte Tillandsia circinata (Bromeliaceae) was observed and collected from six diverse habitats in south Florida. Calcium, K, N, Na, Mg, and P levels were determined in prefruiting, fruiting, and postfruiting rosettes from these plants. The mineral composition varied considerably among growth stages at a site and among sites within growth stages. By weight, Na tended to predominate while the other five elements were usually present at much lower levels. Potassium and P showed pronounced positive correlations with this epiphyte's vigor and reproductive capacity whereas the other elements did not show such correlations. Although T. circinata seems able to tolerate very low nutrient levels, these data suggest that its distribution and vigor are in part determined by nutritional factors which vary with habitat and host type. Plants growing on hosts with a large leaf surface area and where ant nidification is relatively common tend to be more vigorous and fruitful than those occurring in depauperate forests which support a sparse canopy. These latter hosts, however, often harbor numerous small epiphytes which produce a few small capsules per shoot.
PROTEOKALON A NEW GENUS OF PROGYMNOSPERMS FROM THE DEVONIAN OF NEW YORK STATE AND ITS BEARING ON PHYLOGENETIC TRENDS IN THE GROUP
Authors: Scheckler S. E. , Banks H. P.
Published: January 2018

Proteokalon gen. nov. is described from the Upper Devonian Catskill deposits of New York. Two orders of branching and ultimate appendages are preserved' by petrifaction and by compression. The first order bears branches decussately and has a skewed four‐armed protostele that occasionally dichotomizes. Second‐order branches dichotomize rarely and most have T‐shaped or three‐armed protosteles. They bear ultimate appendages alternately, either in lateral pairs, or singly from the abaxial side. These appendages divide several times in one plane. Their vascular strand is terete. Maturation of the primary xylem is mesarch, and it consists of tracheids and parenchyma. Secondary xylem and phloem and a periderm are present. The outer cortex has a system of hypodermal fibers. Proteokalon is most similar to Tetraxylopteris and Triloboxylon of the Aneurophytales. A comparison of the stratigraphic occurrence of Protopteridium, Aneurophyton, Tetraxylopterism, Sphenoxylon, Triloboxylon, and Proteokalon suggests some evolutionary trends among the Aneurophytales.
MORPHOLOGICAL AND PHYSIOLOGICAL DIFFERENTIATION OF PHORADENDRON POPULATIONS IN TEXAS
Authors: May David S.
Published: January 2018

Investigation of the morphology and physiology of the mistletoe, Phoradendron tomentosum subsp. tomentosum, in Texas reveals that the subspecies is differentiated into at least two ecological races, one in north central Texas, the other in south central Texas. The races differ in leaf length/width ratio, fruit diameter, seed set, spike internode length, freeze tolerance, and flavonoid patterns. Clines occur in leaf length/width ratio and fruit diameter between the races, and these characteristics are negatively correlated. The northern race generally exhibits greater freeze tolerance than the southern race. Field observations, herbarium specimens, and a collection of fresh specimens from northeastern Mexico indicate that a third race in the subspecies may exist there. Racial variation within the subspecies appears to permit it to occupy a diversity of habitats. Morphological and physiological patterns within the two Texas races suggest that introgressive hybridization has occurred between them, allowing for the occupation of intermediate habitats.
ON THE ORIGIN OF CULTIVATED RYE
Authors: Stutz Howard C.
Published: January 2018

From extensive cytological, ecological, and morphological studies, it appears that cultivated rye (Secale cereale L.) originated from weedy products derived from introgression of S. montanum into S. vavilovii. Secale vavilovii appears to have been derived from S. silvestre as a consequence of chromosomal translocations. Secale silvestre was, in turn, derived from S. montanum or a common ancestor. Secale africanum, S. dalmaticum, S. ciliatoglume, and S. kuprijanovii appear to be only slightly modified isolated populations of S. montanum. Populations of S. anatolicum are weedy forms of S. montanum, genealogically and chromosomally distinct from the weedy annual forms from which S. cereale arose.
ABSCISSION OF LEAVES AND LEAFLETS IN ACER NEGUNDO AND FRAXINUS AMERICANA
Authors: Moline Harold E. , Bostrack Jack M.
Published: January 2018

A comparative study of leaf and leaflet abscission in Acer negundo and Fraxinus americana was undertaken with special emphasis on leaflet abscission. Leaf fall in both species is accomplished by orderly, fragmentary abscission of leaflets followed by petiole abscission. Leaflet fall was presaged by differentiation of a separation layer at leaflet bases 10–15 days prior to leaflet fall, without an accompanying protective layer. Anatomical studies of petiole abscission revealed early differentiation of a protective layer followed by differentiation of a separation layer at petiole bases just prior to petiolar fall. Abscission at both sites was facilitated by cell division and dissolution of cell walls within separation layers.
EARLY DEVELOPMENT OF THE BARLEY EMBRYO: FINE STRUCTURE
Authors: Norstog Knut
Published: January 2018

The ultrastructure of early stages in embryogenesis in barley was examined. Post‐fertilization shrinkage does not occur. Plasmodesmata were not observed in cell walls of the zygote and outer cell walls of embryos. There is little evidence of cellular specialization in earliest embryonic stages, and planes of cell division tend to be irregular although a pattern of cell disposition characteristic of some grass embryos can be discerned. The embryo appears polarized after 2–3 division cycles, but no evolving of dorsiventrality occurs during this period. A basal supensor cell “anchors” the embryo during early embryogenesis, but by about five division cycles the embryo loses its attachment to the nucellus and is completely surrounded by endosperm. An increase in number of ribosomes and mitochondria takes place during early embryogenesis, and mitochondrial dimensions are reduced. A shift in vacuole distribution occurs.
THE RELATIONSHIP AND ORIGIN OF TSUGA HETEROPHYLLA AND TSUGA MERTENSIANA BASED ON PHYTOCHEMICAL AND MORPHOLOGICAL INTERPRETATIONS
Authors: Taylor Ronald J.
Published: January 2018

Morphological intermediacy between Tsuga heterophylla and Tsuga mertensiana has stimulated controversy concerning the relationship between these two hemlock species and has led to wide acceptance of hybridization as a causative factor of intermediate forms in areas of distributional overlap. In this study, comparative’ chemical analyses were used to test the theory of hybrid derivation of intermediates. Chromatographic analyses were further applied to the phylogenetic ranking of several North American and Asian species of Tsuga and to the examination of the hypothesis that Tsuga mertensiana is a derivative of intergeneric hybridization involving Tsuga heterophylla and Picea sitchensis. Chromatographic data derived from extensive sampling in the western Cascades of Washington led me to conclude that hybridization of Tsuga heterophylla and T. mertensiana is a possible but rare phenomenon and is not necessarily indicated by morphological intermediacy. Phylogenetically both of these species are typical representatives of Tsuga and are distinct from species of Picea. There is, however, some support for the derivation of Tsuga mertensiana by intergeneric hybridization.
CULTURAL FEATURES AND IMPERFECT STAGE OF HYMENOSCYPHUS CAUDATUS
Authors: Kimbrough James W. , Atkinson Merelee
Published: January 2018

Ascosporic cultures were obtained from spore shoots of Hymenoscyphus caudatus growing abundantly on leaves of Acer rubrum. In determining the proper medium, light, and temperature for growth, an Idriella conidial stage was discovered for this fungus. Attempts to induce apothecia to develop under artificial conditions proved unsuccessful.
FURTHER OBSERVATIONS ON THE PHENOMENON OF SECONDARY VACUOLATION IN LIVING CELLS
Authors: Mahlberg Paul
Published: January 2018

Invagination of the plasma membrane in plant cells forms peripheral or endocytic structures which often contain a complement of membrane‐bound vesicles. These structures, or secondary vacuoles, move with the streaming cytoplasm although their velocities are somewhat slower than that for the various organelles within the cytoplasm. They glide over the nucleus or flow from the peripheral cytoplasm onto a transvacuolar strand and continue unabated along the length of a strand. These structures may detach from the plasma membrane as sacs to become positioned in the cytoplasm directly under the tonoplast and project into the primary vacuole. Some endocytic vacuoles may separate from the peripheral cytoplasm and remain free within the primary vacuole; subsequently they can re‐associate with the cytoplasm. While the content and function of these vacuoles are yet to be determined, indirect evidence indicates that they are pinocytic in character since the content of an invagination is confined to the sac upon its detachment from the plasma membrane and is subsequently transported throughout the cell by cyclosis.
STROTHERIA (COMPOSITAE‐TAGETEAE) A NEW MONOTYPIC GENUS FROM NORTH‐CENTRAL MEXICO
Authors: Turner B. L.
Published: January 2018

A new genus Strotheria, containing the single species S. gypsophila, has been described from a locality in north‐central Mexico. It is relatively common on gypsum soils at this site, along with several other gypseous endemics. The genus is presumably related to Dyssodia but differs in having succulent, non‐glandular foliage and only four florets per head. Its chromosome number was determined as n = 8.
DURATION OF CELL CYCLES IN CULTURED ROOTS OF CONVOLVULUS
Authors: Phillips Harry L. , Torrey John G.
Published: January 2018

The durations of the cell cycle in physiologically different regions of the meristem of cultured roots of Convolvulus arvensis were determined by the metaphase‐accumulation technique involving colchicine. The cell cycle in the root cap increases from 13 hr in the actively dividing initials of the first tier to 155 hr in the slowly dividing initials of tiers 2–4 to an indeterminate value for derivatives of the initials in the root cap columella. The cycle times for the cells of the central cylinder and cortex are 21 and 27 hr, respectively. The cells of the quiescent center have a cycle of an estimated 420 hr. The duration of the cell cycle in these different regions is discussed in relation to the increased duration of G1 in slowly or non‐dividing cells. The possible regulation of cell division by the synthesis of a cell‐division factor in the quiescent center is also discussed.
MECHANISM OF SEED DORMANCY IN AMBROSIA ARTEMISIIFOLIA
Authors: Willemsen Roger W. , Rice Elroy L.
Published: January 2018

Dormancy in Ambrosia artemisiifolia seeds was broken by 8 weeks of stratification. Germination of nondormant seeds was greater in light than in continuous darkness. Embryos of freshly harvested seeds were nondormant. Leaching and scarification did not stimulate germination of the dormant seeds. Exogenous gibberellin (GA3) slightly increased germination of intact dormant seeds, and the effect was greatly increased by scarification. Germination was greater in the light in both tests. Exogenous indoleacetic acid did not stimulate germination of dormant seeds. Endogenous gibberellin and auxin content increased during stratification, and there was also a significant increase in GA during post‐stratification at a favorable germination temperature. Inhibitors in the dormant seeds decreased during stratification and post‐stratification. The high concentration of chlorogenic acid present in dormant seeds increased slightly during stratification. An unknown phenol very similar to chlorogenic acid in fluorescence and U.V. absorption significantly increased after 2 weeks of stratification. A significant decrease in the concentration of a second unidentified phenol occurred after 2 weeks of stratification. It is proposed that dormancy in Ambrosia artemisiifolia may be controlled by an inhibitor‐promoter complex. The dormant seed is characterized by high inhibitor and low promoter levels. In the nondormant seed the balance was shifted to favor the promoter. Evidence suggests that the inhibitor involved may be abscisic acid and the promoters may be gibberellin and auxin. The content of auxin may be partially controlled by the concentration of phenols.
OCCURRENCE AND DEVELOPMENT OF A FILIFORM APPARATUS IN THE EGG OF PLUMBAGO CAPENSIS
Authors: Cass David D.
Published: January 2018

Micropylar wall extensions in the egg of Plumbago capensis arise as small pegs of periodic acid‐Schiff's‐positive material soon after the egg is organized. These inward projections of egg wall increase in size, becoming extensive near anthesis. Some branching of the filiform apparatus occurs. In mature embryo sacs the micropylar portion, with the lowermost portion of the egg included, becomes entrenched in the nucellus. The possible significance of this “gametic transfer cell” is discussed in relation to the apparent absence of synergids from the reduced embryo sac of Plumbago.
THE DIFFERENTIATION OF PIGMENTATION IN FLOWER PARTS. VIII. THE EFFECT OF INHIBITORS OF PROTEIN AND RNA SYNTHESIS ON DEVELOPMENTAL CHANGES OF ANTHOCYANINS IN CULTURED PETALS OF IMPATIENS BALSAMINA
Authors: Bibb Philip C. , Hagen Charles W.
Published: January 2018

If inhibitors of protein or RNA synthesis are administered to flower petals of the red genotype (HHHPrPr) of Impatiens balsamina at a very early stage of development, an alteration in the normal pattern of anthocyanin pigmentation results. Whereas control petals are mainly pigmented with acyl pelargonidin‐3,5‐diglucoside and pelargonidin‐3,5‐diglucoside, petals cultured in the presence of inhibitors are mainly pigmented with pelargonidin‐3‐monoglucoside. The complete absence of the more highly substituted forms of pelargonidin in treated petals suggests that the biochemical reactions required for the addition of glucosyl and hydroxycinnamoyl residues to pelargonidin‐3‐monoglucoside have been prevented. The ability to block the normal developmental pattern of pigmentation with these inhibitors suggests that de novo synthesis of active enzymes is required, and as indicated by the effectiveness of actinomycin D, specific RNA synthesis is a necessary prerequisite for the synthesis of the normal anthocyanin complement in this tissue. The ability of the white flowered genotype (llhhpp) to metabolize exogenously supplied pelargonidin‐3‐monoglucoside was found to be prevented by prior culture of immature petals in the presence of DL‐ethionine. The data indicate that the enzymes required for this ability are not products of induction by the substrate but rather their presence is a normal feature of petal development. Treatment with inhibitors has failed to produce any inhibition in the formation of specific anthocyanins found in the flower petals of some other genotypes of I. balsamina.
EFFECTS OF SPACE FLIGHT (BIOSATELLITE II) AND RADIATION ON FEMALE GAMETOPHYTE DEVELOPMENT IN TRADESCANTIA
Authors: Marimuthu K. M. , Schairer L. A. , Sparrow A. H. , Nawrocky Marta M.
Published: January 2018

The mode of female gametophyte development and the cytological effects of orbital flight factors, with and without radiation, on embryo sac development were studied in Tradescantia clone 02 flown in Biosatellite II. One package of 32 rooted inflorescences was exposed during the free‐flight phase of the two‐day orbital flight to about 220 R gamma radiation from an 85Sr source, and a nonirradiated package was flown as a flight control. Two similar packages, one irradiated and one unirradiated, were maintained in a ground‐based vehicle as concurrent nonflight controls. Various postflight ground experiments were conducted in an attempt to associate with specific flight factors the effects observed in the orbited plants. Mature ovaries were fixed daily as the flowers opened for at least 20 days after the treatment, sectioned, stained, and analyzed for the rate of embryo sac abortion and other developmental abnormalities. The embryo sac in Tradescantia clone 02 is eight‐nucleate with a Polygonum type of development. Irradiation during megasporogenesis produced an increased rate of embryo sac abortion and this radiation effect was greater in the environment of the flight vehicle than in the nonflight vehicle. This effect may be due to an increase in concentration of ethylene in the flight vehicle. A synergism between some undetermined flight factor and radiation was found to produce underdeveloped embryo sacs. Malfunctioning of the spindle, most probably due to free flight, was evidenced by the increased number of embryo sacs with misoriented nuclei.
STRUCTURALLY PRESERVED PHLOEM ZONE TISSUE IN RHYNIA
Authors: Satterthwait Donna F. , Schopf J. William
Published: January 2018

Optical microscopic studies of longitudinal sections of permineralized Rhynia axes from the lower (?) Devonian Rhynie Chert of Scotland have revealed the occurrence of numerous pores, 3–8 μm in diam, distributed along lateral cell walls in the zone of tissue commonly regarded as phloem. In face view, these pores appear to be composed of circular subunits less than 1 μm in diam. A conductive function for the complex tissue of the Rhynia phloem zone seems evidenced by the occurrence of these pores and by the thin‐walled, elongate, tapered nature of the component cells.
ULTRASTRUCTURAL STUDIES OF BROWN ALGAL NUCLEI
Authors: Neushul M. , Dahl A. L.
Published: January 2018

The nuclei of four brown algae (Dictyota, Padina, Zonaria, and Dictyopteris) have been studied using sectioning and freeze‐etching techniques. A comparison of the results obtained with those of earlier workers suggests that nuclear structure may be similar throughout the Phaeophyta. Freeze etching has revealed striking bands of nuclear pores and arrays of particles within the nuclear envelope membrane, which are reported for the first time. Particular attention has been given to nuclei in experimentally manipulated cells of Zonaria, where changes in nucleolar size, nucleoplasmic staining, nuclear envelope configuration, and in the contents and extent of the perinuclear cytoplasm were found to occur. These changes appear to be related to whether the apical cells and nuclei were active, dormant, or in the process of division. The Zonaria nucleus may control the arrangements of microtubules, cellular membranes, and organelles seen in the apical cells of this brown alga.
GROWTH REGULATION BY ETHYLENE IN FERN GAMETOPHYTES. III. INHIBITION OF SPORE GERMINATION
Authors: Edwards Maurice E. , Miller John H.
Published: January 2018

Spores of Onoclea sensibilis were investigated for inhibition of germination by ethylene. A curve of germination against ethylene concentration indicated a “threshold” type of response, but percentage of spore germination was not influenced either by the density of the inoculum or by the presence of 1 % sucrose in the culture medium. Ethylene totally inhibited dark germination, but in white light reversal of inhibition was possible in about 50% of the germinating spores. Time‐course studies revealed that in imbibed spores ethylene inhibited germination in the first 3 ± 1 hr of illumination. Dose‐response curves of light intensity vs. germination indicated that the response to light differed in the presence and absence of ethylene. Recovery from inhibition was possible once ethylene was allowed to escape, and the rate of recovery was accelerated by light.
ANEUPLOIDY IN CITRUS
Authors: Esen Asim , Soost Robert K.
Published: January 2018

Analyses of ploidy levels in progenies from 2x x 2x, 2x x 4x, 4x x 2x, 4x X 4x, and 4x x OP crosses during embryogenesis and seed germination indicate that the progenies include an array of aneuploids. The occurrence of some of the aneuploids was previously unreported. Most of the aneuploids were from 2x x 4x crosses, which yielded the largest number of progeny. Chromosome counts from embryos and endosperms of sectioned young seeds provide evidence that aneuploids originate in progenies of 2x x 4x crosses from the functioning of male gametes with more or fewer chromosomes than 2x = 18 in syngamy with reduced and unreduced female gametes. The origins of aneuploids in progenies from other crosses are problematical at this writing.
DIFFERENTIATION OF THE GREEN ALGA CODIUM FRAGILE
Authors: Ramus J.
Published: January 2018

Clonal cultures of Codium fragile were established from both swimming cells and vegetative filaments. In the laboratory axis primordia differentiate from heterotrichous juveniles only when cultures are agitated on a reciprocating shaker. The shear forces created by mechanical agitation are essential both for initiation and maintenance of primordia. Contact guidance of growing coenocytic filaments indicates mutual adhesion of filaments as the basis for the differentiation process.
COMPARATIVE ANATOMY OF THREE SPECIES OF THE APOPHYLLOUS GENUS GYMNOPHYTON
Authors: Böcher T. W.
Published: January 2018

The anatomy of three species of Gymnophyton has been studied by light and electron microscopy. The species are essentially leafless and morphologically they are very much alike, but they differ anatomically and can be characterized just by their anatomical differences. SEM revealed great differences in stomatal structure, orientation, and dimensions. Micro‐channels (ectodesmata) in the guard cell walls were disclosed in great numbers in G. isatidicarpum by using interference contrast microscopy, and these structures are thought to function as pathways for wax precursors. In older stems of this species the epidermis and cortical palisade tissue are isolated by a continuous periderm layer. Before dying, the palisade cells undergo alterations, and the stomata are permanently closed by cuticular plugs between the guard cells or by fusion of the swollen adaxial parts of the subsidiary cells. Similar permanent closure mechanisms are not found in G. polycephalum and G. robustum, which also deviate by having their stomatal openings orientated at a right angle to the axis of the stem and by the occurrence of collenchyma strands instead of fiber strands along the stem corner ribs. Gymnophyton polycephalum and G. robustum seem to be more closely related to each other than either is to G. isatidicarpum, but they differ markedly from one another in the size and structure of their stomatal complexes.
CAMELLIA + ‘DAISY EAGLESON,’ A GRAFT CHIMERA OF CAMELLIA SASANQUA AND C. JAPONICA
Authors: Stewart R. N. , Meyer F. G. , Dermen Haig
Published: January 2018

We have described a new, distinct camellia cultivar, Camellia + ‘Daisy Eagleson’ (Byrd ex Meyer), found on a rootstock of hexaploid C. sasanqua Thunb. ‘Maiden's Blush’ on which a scion of diploid C. japonica L. had been grafted. The new cultivar is a graft chimera with epidermal tissue from C. sasanqua and the internal tissue from C. japonica. Many characters expressed and measured at the cellular or tissue’ level showed complete independence in the chimera. These included chromsome number, anthocyanin synthesis, pH, cell size, and fragrance. Some characters expressed at the organ or whole plant level showed an interaction between the two components. These included floral morphology, leaf size, time of bloom, bud hardiness, and growth habit. One entirely new character we found was the presence of 6–8 styles in the chimeral flowers in contrast to the three styles typical of the component species. While the two components grew together in apparent harmonious and stable fashion, we have recovered each of the pure, homogeneous component cultivars a number of times from tissue replacement and displacement phenomena in the shoot and as adventitious shoots from roots. ‘Daisy Eagleson’ is only the third, fully‐authenticated, woody graft chimera.
ON SEXUAL AGGLUTINATION AND MATING‐TYPE SUBSTANCES IN ISOGAMOUS DIOECIOUS CHLAMYDOMONADS. III. THE SENSITIVITY OF SEX CELL CONTACT TO VARIOUS ENZYMES
Authors: Wiese Lutz , Hayward Patricia C.
Published: January 2018

The components responsible for sex cell contact in dioecious Chlamydomonas species have been characterized by their sensitivity to enzymes. The mating‐type substances, which are glycoprotein complexes according to the analysis of the corresponding isoagglutinins, were incubated with proteases, glycosidases, and with sulfatase. An enzyme may or may not affect both gamete types of a species or it may discriminate between the sexes, eliminating one mating‐type activity only. In no case was an incapacitation of a given gamete type based upon the detachment of the proper contact component as an isoagglutinin or as a functionally univalent structure with a specific receptor‐blocking power against the complementary type. Inactivating enzymes seem to interfere with the surface configuration essential for gamete contact or to eliminate actual contact sites. The compilation of data for six taxa reveals a complex sensitivity pattern of the gametes’ agglutinability. Two types of interactions appear to occur. In C. reinhardti and C. chlamydogama the contact mechanism seems to depend on an interaction between two proteinaceous structures. In C. eugametos and C. moewusii definite proof was obtained for a contact based upon a carbohydrate‐protein interaction. In the (+) sexes of C. eugametos and C. moewusii syngen II, α‐glycosidically bound terminal mannose residues are essential for the contact. Neither β‐galactosidase, neuraminidase, or sulfatase incapacitate the mating‐type substances in situ.
ULTRASTRUCTURE OF ASCOCARP DEVELOPMENT IN SPORORMIA AUSTRALIS
Authors: Blanchard Robert O.
Published: January 2018

Thin sections taken from intact ascocarps were examined to trace the developmental sequence of ascocarp formation in Sporormia australis Speg. The ascocarp originated from a uninucleate vegetative hyphal cell which underwent repeated divisions and formed an ascostroma. In the center of the young ascostroma a cavity formed, apparently from cell disintegrations, and enlarged as the ascocarp enlarged. Within the cavity pseudoparaphyses developed from undifferentiated pseudoparenchymatous cells at the apex of the cavity and extended downward. Ascogenous hyphae arose from proliferating uninucleate cells at the base of the cavity. As the ascocarp matured, the pseudoparenchymatous cells differentiated into three layers, none of which were considered homologous to the perithecial wall lining the cavity of pyrenomycetes. The cells of the apex were not differentiated into layers and light microscopy revealed the presence of an ostiole through which bitunicate asci discharged their eight 4‐celled ascospores.
HISTOCHEMICAL LOCALIZATION OF ENZYMES IN TAPINANTHUS BANGWENSIS: ACID PHOSPHATASE
Authors: Onofeghara F. A.
Published: January 2018

The distribution of acid phosphatase in the tissues of Tapinanthus bangwensis, a semiparasitic member of the Loranthaceae, and some of its hosts was studied. It has beer possible to work out convenient routine methods of pretreating tissues for histochemical enzyme localization, to modify, where necessary, conventional histochemical techniques for the localization of acid phosphatase, and to evaluate the azo‐dye and metal‐salt techniques at the optical level. Histochemical localization showed generally widespread activity and similarity in distribution for this enzyme in the parasite and host tissues. Although there is no direct correlation between these localizations and host‐parasite relationships, the bearing that the localizations may have on such relationships is discussed in the light of the distributional evidence and the role usually ascribed to this enzyme.
THE SHOOT APICAL ONTOGENY OF THE PICEA ABIES SEEDLING. II. GROWTH RATES
Authors: Gregory Robert A. , Romberger J. A.
Published: January 2018

Shoot apices of greenhouse‐reared Picea abies seedlings undergo a sequence of age‐related developmental changes before closely approaching a steady‐state condition when about 140 days old. Apical dome diameter and height increase with seedling age. Thus, although the relative volume growth rate of the apical dome declines as the seedlings age, the increase in size of the mean apical dome itself is so large that the absolute volume of new tissue generated per day still increases several fold. Therefore, the observed decline in plastochron duration, decreases in relative growth rates per plastochron, increase in absolute volume growth per plastochron, and increase in tissue doubling time with increasing age are all mutually compatible. The apical dome of the mean 20‐day‐old plant produced about 110,000 μ3 of tissue per plastochron of 18.5 hr, or about 140,000μ3 per day. Relative volume growth rate was about 20 % per day. At that rate about 4.4 plastochrons or 82 hr would be needed to double a unit volume of apical dome tissue. In contrast, the apical dome of the mean 140‐day‐old plant produced about 220,000μ3 of tissue per plastochron of 5.7 hr, or about 940,000 μ3 per day. Relative volume growth rate was about 12 % per day; consequently, about 23 plastochrons or 130 hr would be needed to double a unit volume of apical dome tissue. Further analysis indicated that an internode, newly initiated by the mean 140‐day‐old plant, increased in volume at the rate of 7.46% per plastochron or 31.5% per day for the first 10 plastochrons. Methods are presented for estimating vertical, radial, and volume growth rates at any level of the shoot apex when steady‐state conditions prevail.
EFFECT OF ETHYLENE ON CELLULAR DIFFERENTIATION IN ETIOLATED PEA SEEDLINGS
Authors: Apelbaum Akiva , Fisher Jack B. , Burg Stanley P.
Published: January 2018

Ethylene (50 ppm) and 2,4‐D (1 mm) inhibit xylogenesis and completely prevent fiber lignification in the third internode of etiolated pea seedlings (Pisum sativum var. Alaska) during 96–240 hr of treatment. When ethylene is removed after 72 hr, normal differentiation resumes; thus the gas causes no irreversible damage to the cells. A combined treatment with 50 ppm ethylene and 50 μm 2,4‐D or treatment with 1 mm 2,4‐D alone causes inhibition similar to that observed with 50 ppm ethylene, and 50 μm 2,4‐D is partially effective. The inhibition of xylogenesis and fiber lignification caused by 2,4‐D is partly or wholly due to auxin‐induced ethylene production.
ULTRAVIOLET REFLECTANCE CHARACTERISTICS IN FLOWERS OF CRUCIFERS
Authors: Horovitz Auguste , Cohen Yoel
Published: January 2018

Ultraviolet reflectance properties of flowers in 26 East Mediterranean wild species and three cultivated species of the Cruciferae are surveyed. These properties were disclosed by photography of fresh or herbarium specimens through a visible‐light absorbin filter. The so‐revealed spectral polymorphism is related to the previously known visible flower colors. Ultraviolet floral patterns which act as nectar guides to pollinators are described. Hitherto unreported patterns were found to result from ultraviolet absorption by sepals, ultraviolet reflection from anther tips, and, in one case, ultraviolet absorption by a peripheral part of the corolla. In some cases patterns differ between closely related taxa and could therefore be of diagnostic value.
QUANTITATIVE STUDY OF NUCLEIC ACIDS AND PROTEINS IN THE SHOOT APEX OF SINAPIS ALBA DURING TRANSITION FROM THE VEGETATIVE TO THE REPRODUCTIVE CONDITION
Authors: Jacqmard Annie , Miksche Jerome P. , Bernier Georges
Published: January 2018

Quantitative changes in DNA, histone, RNA, and total protein have been measured in meristematic cells during floral evocation.2 A single 22‐hr, long‐day exposure induced two‐month‐old vegetative plants of Sinapis alba to flower. Periodic collections of shoot apices were made and stained with Schiff's reagent (DNA), azur B (RNA), alkaline fast green (histone), and naphthol yellow S (total protein). The two‐wavelength method was used for DNA and histone measurements and the one‐wavelength, two‐area procedure was chosen for RNA and total protein determinations. The DNA and histone amounts per cell decreased to a minimum value 34 hr after treatment, and most of the nuclei shifted from 4C to 2C values. DNA and histone quantities paralleled each other from 34–46 hr, after which time the histone values continued to increase and the DNA values decreased. The RNA values increased rapidly after treatment as did the total protein quantities, after a slight decrease at 34 hr concurrent with the 4C to 2C cell population shift. The significance of these events is discussed in relation to the changes which were previously described in the shoot apex of Sinapis in transition to flowering.
INFLORESCENCE AND FLOWER STRUCTURE IN NYPA FRUTICANS (PALMAE)
Authors: Uhl Natalie W.
Published: January 2018

Details of organogenesis, anatomy, and some aspects of histogenesis are described for the inflorescence units and flowers of the mangrove palm, Nypa fruticans. The genus is of special interest in evolutionary studies because of its disjunct morphology and substantial fossil record. The inflorescence is an erect monopodial axis bearing 7–9 lateral branches and ending in a pistillate head. The lowest of the lateral branches bears up to six orders of branches, the next ones progressively fewer, and the uppermost is usually unbranched. Lateral branches of all orders end in thick spicate, staminate rachillae. The rachillae and the pistillate head consist of spirally inserted sessile flowers, each borne in the axil of a bract. Staminate and pistillate flowers are similar in structure. Both have three separate sepals and three separate petals, which are loosely closed in bud. Staminate flowers have no pistillodes; nor are there any staminodes in the pistillate flower. The androecium consists of a stalk bearing three anthers distally and is shown to represent three stamens with filaments congenitally fused and anthers connate by the ventral faces of the connectives. The pistillate flower has three separate carpels, which expand rapidly so that by anthesis they much exceed the perianth. Each carpel is cupulate in shape, with a two‐crested distal opening, and receives ca. 150 vascular bundles, many of which may branch dichotomously. No dorsal or ventral bundles can be definitely distinguished, but a ventrally open ring of 10–12 bundles surrounding the locule matures first. Allometric growth clearly accounts for much of the morphological disjunction in the reproductive organs of Nypa contrasted with those of other palms. Resemblances to coryphoid, ceroxyloid, arecoid, and cocosoid palms are indicated by these studies. Different combinations of characters and several distinctive features justify a separate major taxonomic category for this genus within the Palmae.
ARTIFICIAL HYBRIDIZATIONS IN THE SUBTRIBE PERITYLANAE (COMPOSITAE–HELENIEAE)
Authors: Powell A. Michael
Published: January 2018

Artificial hybridizations were conducted with 37 species of four genera of the subtribe Peritylanae (Compositae). Crossability, pollen stainability, and meiotic behavior were examined for most of the resulting 61 F1 hybrid combinations. Intergeneric hybrids involving Amauria, Eutetras, Pericome, and Perityle, and infrageneric hybrids involving Perityle were readily obtained. Lower crossability and hybrid fertility were displayed by intergeneric crosses. The infrageneric crosses of Perityle were organized into two categories, intersectional and infrasectional, based upon the taxonomic sections that are recognized for the genus; sect. Pappothrix, sect. Laphamia, and sect. Perityle. In general, the crossability and hybrid fertility of intersectional crosses was markedly higher than that of intergeneric crosses. The results suggest a closer relationship between the three taxonomic sections of Perityle than between Perityle and other genera of the subtribe.
CELL PROLIFERATION IN COMPLEX TISSUES: THE CONTROL OF THE MITOTIC CYCLE OF CELL POPULATIONS IN THE CULTURED ROOT MERISTEM OF SUNFLOWER (HELIANTHUS)
Authors: Hof Jack Van't , Rost T. L.
Published: January 2018

Experiments were performed with cultured primary root tips of sunflower (Helianthus annuus var. Russian Mammoth) to determine: (1) if progression in the mitotic cycle of meristematic cells was nutritionally controllable by carbohydrate starvation and replenishment; (2) where in the mitotic cycle control was effected; and (3) whether nutritional deprivation could be used to detect phenotypically different subpopulations in a complex tissue. Meristematic cells were rendered stationary by carbohydrate starvation, as indicated by the absence of cell division; this condition was reversed by carbohydrate provision. After 72 or 96 hr of starvation most cells stopped in G1 (80–90%) and G2 (10–20%), and a very few (“leaky” cells) continued to enter S. “Leaky” cells represent a small population with an S period of approximately 4.1 hr that either lack a principal control point in G1 or have an unusual metabolism whereby the control point requirements are met and have a carbohydrate dependence for mitosis. Though phenotypically different, no specific functions can be attributed to “leaky” cells at this time.
WOUND RECOVERY BY PITH CELL REDIFFERENTIATION: STRUCTURAL CHANGES
Authors: Sussex Ian M. , Clutter Mary E. , Goldsmith Mary Helen M.
Published: January 2018

The redifferentiation of tobacco pith cells was examined in two experimental systems: wounds recovering from an incision that severed vascular tissue of the stem, and induced differentiation of excised pith responding to indoleacetic acid supplied locally via pipets inserted into the tissue. In both systems there was an initial period during which cell division was resumed and the pith cells were cleaved into numerous small cells. This was followed by redifferentiation of some of the divided cells as tracheary elements and, especially in the stem, by the formation of a cambial meristem that produced further xylem and phloem. In the stem the size of the wound meristem decreased as the wound was made further from the shoot apex, and in the cultured pith tissue it was demonstrated that the size of the dividing zone increased with the concentration of auxin supplied. Auxin was, therefore, demonstrated to be limiting in the division phase of redifferentiation. The sequence of redifferentiation in the two experimental systems resembled the normal ontogeny of vascular tissues in the intact plant sufficiently that these systems could be used to investigate the relationship between cell differentiation and auxin transport.
ONTOGENY AND STRUCTURE OF THE SECONDARY PHLOEM IN EPHEDRA
Authors: Alosi Margaret C. , Alfieri Frank J.
Published: January 2018

The secondary phloem in Ephedra is atypical of the gymnosperms in general and exhibits several angiosperm‐like characteristics. The ray system of the conducting phloem consists of parenchymatous, multiseriate rays. The axial system contains parenchyma cells, sieve cells, and unusual albuminous cells reminiscent of the specialized parenchyma cells found in some angiosperms. These cell types may intergrade with each other. P‐protein in the developing sieve element appears early in the form of a single, ovoid slime body. Later, smaller slime bodies appear and quickly disperse. In the mature sieve element the single, ovoid slime body is lost, and P‐protein is then evident in the form of a parietal cylinder, thread‐like strands, amorphose globules, or a slime plug. Necrotic‐appearing nuclei are commonly found in mature sieve cells.
ONTOGENY OF FOLIAR VENATION IN EUPHORBIA FORBESII
Authors: Herbst Derral
Published: January 2018

Six species of Euphorbia endemic to the Hawaiian Islands have disjunct veins as a normal component of their foliar anatomy. An ontogenic study of the foliar venation of one of these species, E. forbesii, showed a normal development of the foliar procambium as determined by previous studies of dicotyledonous leaves. The disjunct veinlets are isolated early in the histogenesis of the intersecondary veins when certain procambial cells fail to differentiate into vascular tissue. It appears that these cells develop into normal parenchymatous cells of the ground tissue. It is suggested that these cells are physiologically distinct from the rest of the procambial cells. In no instance was a tracheary element seen which appeared to have arisen independently of the normal procambial reticulum.
“PRE‐CRETACEOUS” ANGIOSPERMS FROM UTAH: EVIDENCE FOR TERTIARY AGE OF THE PALM WOODS AND ROOTS
Authors: Scott Richard A. , Williams Paul L. , Craig Lawrence C. , Barghoorn Elso S. , Hickey Leo J. , MacGinitie Harry D.
Published: January 2018

Our studies indicate a Tertiary age for silicified palm roots and wood from near Redmond, Utah, recently described as the first unequivocal angiosperms from pre‐Cretaceous strata. Field relationships and petrographic analysis demonstrate that the rocks in which the palm roots occur in place, supposedly beds of the Jurassic Arapien Shale, are actually strata of the Dipping Vat Formation of middle Tertiary age. The type and only localities of the palm woods designated as Palmoxylon pristina Tidwell and P. simperi Tidwell are on the Arapien Shale; however, unequivocal evidence that the specimens were in place is lacking. Both of these localities are situated on drainages topographically below an angularly unconformable Tertiary sequence including the Dipping Vat Formation. In the immediate area the Dipping Vat Formation contains abundant in situ palm wood and roots. Slump blocks of this sequence, some of them containing palm material, were found in the vicinity of both type localities. Sections of palm wood from the Dipping Vat Formation display the same anatomical features that characterize Palmoxylon pristina and P. simperi, including such characteristic attributes as the presence of fiber strands in the ground tissue. The probability that woods of P. pristina and P. simperi, rather than having originated in the Arapien Shale, were transported from the Dipping Vat Formation during post‐Tertiary erosion makes a Jurassic age for these fossil angiosperms insupportable.
ANTHOCYANINS OF DIMORPHOTHECA (COMPOSITAE). I. IDENTITY OF PIGMENTS IN FLOWERS, STEMS, AND CALLUS CULTURES
Authors: Ball Ernest A. , Harborne Jeffrey B. , Arditti Joseph
Published: January 2018

Anthocyanins isolated from ray flowers, disk florets, stem, and callus cultures of Dimorphotheca sinuata were identified and found to be cyanidin‐3‐glucoside and dephinidin‐3‐glucoside. The anthocyanins of the callus cultures were of the same identity as those in the whole plant, demonstrating that these glucosides are produced in the same manner under autophytic and heterophytic conditions. The use of this callus culture in experimental studies of anthocyanin production is discussed.
FINE STRUCTURE AND COMPOSITION OF THE EGG APPARATUS BEFORE AND AFTER FERTILIZATION IN QUERCUS GAMBELII: THE FUNCTIONAL OVULE
Authors: Mogensen H. Lloyd
Published: January 2018

A study of the egg apparatus of Quercus gambelii was made at both the light and the electron microscope levels. This investigation was concerned primarily with the changes that occur in these cells before and after the process of fertilization and what role, if any, is played by the synergids in this phenomenon. The synergids before fertilization are, on the basis of ultrastructure, healthy, intact, functional cells. They have numerous mitochondria, dictyosomes, endoplasmic reticulum, ribosomes, and a typical nucleus. A prominent filiform apparatus is present, but the cell wall only extends a short distance around the micropylar end of the cells. Just before fertilization, one of the synergids degenerates. This is the synergid that receives the pollen tube and its discharge, including both male gametes. Dictyosomes increase in number and activity in the other synergid (persistent synergid) after fertilization. Eventually a complete cell wall forms around both of the synergids. No plasmodesmata are present in these walls. The egg has numerous mitochondria, dictyosomes, endoplasmic reticulum, and ribosomes, both free in the cytoplasm and attached to the endoplasmic reticulum. Lipid bodies are characteristic of this cell. A cell wall is present only around the micropylar end of the egg. After fertilization, little change occurs in the zygote. The number and activity of the dictyosomes increase, apparently in correlation with cell wall formation. The number of lipid bodies increases. The zygote is approximately the same size as the egg. Plastids are scarce, and starch grains are typically absent from all cells of the egg apparatus. It is suggested that the synergids function in the secretion of chemotropic substances that guide the growth of the pollen tube. Comparisons are made between the egg apparatus of Quercus gambelii and that of the other plants studied thus far.
SOME EFFECTS OF 2‐CHLOROETHYL TRIMETHYL AMMONIUM CHLORIDE (CCC) ON THE CHLOROPHYLL AND CAROTENOID CONTENT OF JACK BEAN LEAVES
Authors: Greenwald Stephen M.
Published: January 2018

0.1m 2‐chloroethyl trimethyl ammonium chloride is known to cause bleaching of leaves in intact plants. In this experiment chlorophyll and carotenoid levels were examined by standard procedures in order to gain some insight into the nature of this response. It was found that chlorophyll was destroyed, with white areas appearing on the leaves, and that a drop in carotenoid level preceded the destruction. Thus, the results indicate that CCC interferes with isoprene metabolism, lowering carotenoids, and allowing chlorophyll to be photooxidized. This effect on carotenoids has not been previously reported.