bluuebunny/crossref_metadata_2025_split huggingface dataset:
The mechanism of calcium and magnesium uptake from sea water by a marine bacterium
Authors: Carroll J. J. , Greenfield L. J. , Johnson R. F. 
Published: February 2005

AbstractPreviously, the precipitation of calcium carbonate by marine bacteria had been described in which bacteria occupy the nucleus of micro‐aragonite crystals. The mechanism of the process of calcium‐binding by the cells is the subject of this study.Sea‐water cultures of Pseudomonas piscicida (Bein) Buck et al. (A.T.C.C. 15057) were grown under standardized conditions (1% peptone‐artificial sea water, 25°C). Cells of various ages were collected and analyzed for calcium and magnesium content under various conditions. Material composing cell walls was fractionated and analyzed for low molecular weight components.Cells up to a week old (1% peptone‐artificial sea water) increase their content of calcium from 0 to 55% of the dry weight. Furthermore the Ca/Mg ratio in young, actively growing cells (up to 24 hours old) is one‐fifth (approximately that of sea water). By 72 hours, the ratio is 1/2.5. At one week, it is 1/1, and by two weeks calcium content exceeds that of magnesium.Concentration of the alkaline‐earth elements is primarily by the cell envelope, particularly by the muco‐polysaccharide fraction. This fraction constitutes 20–25% of the dry weight of cells during rapid growth but increases to 47–52% of dry weight after one week. Binding of alkaline earths to active sites of muco‐polysaccharide is probably by hydrogen bonds and London interaction forces, as removal of the elements by washing is readily accomplished. In addition, a ready source of calciumactive ligands is available in the ammonia produced in quantity by the bacteria. The complex formation by ammonia and Ca, coupled with the increase in pH, favors binding of calcium over that of magnesium by the cells.
Studies on synchronously dividing cultures of Euglena gracilis Klebs (strain Z). I. Attainment and characterization of rhythmic cell division
Authors: Edmunds Leland N. 
Published: February 2005

AbstractEuglena gracilis Klebs (strain Z) was grown synchronously on an aerated, inorganic salt medium at 25°C under a LD: 16, 8 or LD: 14, 10 light‐dark cycle (light intensity of 3,500 lux). In either cycle balanced growth occurred with a doubling of cell number every 24 hr. until limiting conditions of light intensity were reached, due to mutual shading, at about 1.0 – 1.5 × 105 cells/ml. An increase of light intensity to 7,000 lux permitted balanced growth to occur to higher cell concentrations, but with no significant change in generation time. With both photofractions, the fission burst during any given cycle began 13–14 hr after the onset of the light period and continued for about 9–11 hour. Synchrony was slightly greater in the LD: 14, 10 cycle with division confined almost entirely to the dark period; this regime was later adopted for metabolic studies. Synchronous cell division was lost in continuous bright light (3,500 or 7,000 lux), continuous darkness, and in some continuous dim light regimes. The addition of certain organic substrates to the medium resulted in a breakdown of synchrony also, and logarithmic growth ensued. The generation time of cells in either continuous bright light, or with ethanol (0.006 M) and a LD cycle was 11–12 hr.
Destruction of mouse and rat embryo cells in tissue culture by lymph node cells from unsensitized rats
Authors: Ginsburg Haim , Sachs Leo 
Published: February 2005

AbstractA specific destruction of embryo monolayers was obtained in tissue culture, by growing suspensions of lymph node cells from unsensitized adult random bred rats, on mouse and on randomly bred rat monolayers. Mouse monolayers were lysed partially or completely in all the experiments. When two different batches of rat monolayers were used, the first batch was destroyed in three out of six experiments and the second in one out of five. The earliest destructive effect with unsensitized cells was observed on the sixth day. Destruction of monolayers followed the appearance of large numbers of large lymphoid cells with pyroninophilic cytoplasm. Cultures of unaffected rat monolayers were different, in that there was a prolonged survival of small lymphoctyes with the formation of lymphocyte aggregates in which large lymphoid cells appeared.When large lymphoid cells from destroyed monolayers were transferred to new monolayers of the same type, a complete destruction of the monolayers occurred as early as 16 hours after cell transfer, but when transferred to an unrelated type, (from mouse to rat or fom an unaffected batch of rat to the other batch or to mouse), the monolayers were not destroyed. The destructive effect was transferrable by washed large lymphoid cells, but not by cell‐free medium. There was no monolayer destruction with adult rat thymus cells. Tests for a possible viral injection as a contributing cause to the monolayer destruction were negative.The results indicate that a heterograft and a homograft response have been initiated in tissue culture by lymph node cells from unsensitized rats.
The cloning of normal “Mast” cells in tissue culture
Authors: Pluznik Dov H. , Sachs Leo 
Published: February 2005

AbstractA method is described for the cloning of normal mouse “mast” cells in tissue culture in a soft agar medium. The colonies contain cells in different stages of differentiation. It was shown that a colony can be initiated by a single colony forming unit, and that colonies are formed as a result of cell multiplication.Cell suspensions from adult spleen gave about 3 colonies per 105 cells seeded. A re‐cloning of these colonies gave about 3 colonies per 103 cells seeded.The frequency of colonies from SWR mice was higher with adult spleen than with adult thymus. No such colonies were obtained with adult lymph node cells.The formation of colonies was shown to require the presence of an embryo cell feeder layer. Since the feeder layers were seeded underneath the agar, the results indicate that the substance(s) required for the growth and differentiation of “mast” cells can pass through agar.
Molting in an amphibian, diemyctylus
Authors: Adolph E. F. , Collins H. H. 
Published: February 2005

AbstractThe shedding of epidermis in this species, as in most amphibia, is periodic. A single outer layer of cells separates nearly simultaneously over the whole body; two hours to ten days may be required for the process. In the first three months of laboratory existence the average frequency of molting was 9 per cent. In nature the frequency was only 2 per cent; this increased during the life in confinement in five months up to 25 per cent. Death in the laboratory was usually preceded by numerous molts.The time of a molt is not normally determined by any one of a number of ordinary external conditions which were modified; but nevertheless several means were found of inducing molting. These were, in order of their efficacy: bandaging with gauze on body or tail, wrapping the body with thread, stitching the body wall, applying hot water, and transplanting skin. Molting frequencies up to 98 per cent may thus be obtained.Since molting is periodic and simultaneous, it is evidently coordinated. Experimental induction requires a latent period of six to ninety‐six hours, depending upon the stimulus. Recent skin grafts molt with the host, so that the coordination is probably chemical. The primary significance of molting in all groups of animals is possibly the getting rid of unautolyzable waste materials, i.e., worn epithelial structures.
The reproductive system of apotettix eurycephalus hancock
Authors: Harman Mary T. 
Published: February 2005

AbstractThe female reproductive system comprises the ovaries, oviducts, vagina, spermatheca, and spermathecal gland. No colleterial glands are present. The ovaries are paired and each is composed of about eighteen ovarian tubules terminating in a cup‐shaped modification of the oviduct—the egg calyx. The epithelial lining of the oviduct is glandular. The spermatheca, a bladder‐shaped sac situated dorsal to and between the two ovaries, opens into the vagina near the exterior and is filled with spermatozoa after copulation. Spermatozoa have not been found in any other part of the female. Dorsal to the spermatheca and lying against it is the spermathecal gland. It is connected with the spermatheca by an elongate spermathecal duct.The male reproductive system comprises the testes, vas deferens, accessory glands, and the penis. Each testis is composed of eight to ten cone‐shaped follicles, which are composed of a number of cysts so arranged as to appear segmented. All of the cells of each cyst are in approximately the same stage of development. No seminal receptacle is present. Each follicle is connected with the vas deferens by an efferent tube. The paired vas deferens opens into the sac‐like intromittant organ or penis. The terminal portion of the penis may be everted, and when everted is conical in shape. At its base is a thin chitinous collar, the margins of which are thickened, forming ridges.
The life‐cycle in the ciliate Didinium nasutum with reference to encystment
Authors: Beers C. Dale 
Published: February 2005

AbstractThree groups of pure lines of diverse clones of Didinium nasutum were maintained in isolation cultures for 778, 786, and 457 generations, respectively, without exhibiting any decrease in fission rate or any increase in encystment rate or death rate. These lines were supplied with Paramecium caudatum in such numbers that a surplus of food was present at all times.Three other groups of lines of the same clones were established simultaneously and cultured in parallel with the preceding groups, but the food of each of these lines was limited to nine paramecia per line daily. The fission rate of these lines fell to zero and the encystment rate increased to 100 per cent after 155, 165, and 113 generations of culture, respectively. The death rate increased appreciably in these lines prior to encystment.Other groups of pure lines were cultured on a diet limited to six paramecia per line daily. These lines encysted after approximately fifteen generations of culture.This evidence indicates that there is nothing in the nature of a definite life‐cycle in Didinium and that diminished vitality and encystment do not result from the passage of generations, but from inadequate and unfavorable cultural conditions–specifically, from in‐sufficient food. It shows further that it is possible to induce cycles with reference to encystment in Didinium by limiting the food supply and to vary the length of the cycles by varying the quantity of food.
Studies of the life‐cycle of Tetramitus rostratus Perty
Authors: Bunting Martha 
Published: February 2005

AbstractThe flagellate, Tetramitus rostratus Perty, appeared in cultures of certain amoebae obtained from the coecum of rats. In a typical life‐cycle a cyst, planted in an appropriate medium, gives rise to an amoeba which may divide a number of times, but eventually some of the amoebae transform into flagellates identical with Tetramitus rostratus. These divide frequently through several days, sometimes for weeks or months, and then transform back to amoebae which become encysted.During excystment the smooth cyst wall dissolves. Usually both the amoeboid and flagellate phases pass into a “gel” state during division. A “gel” state sometimes occurs during transformation. The time required for transformations varies from a few minutes to several hours.Many culture media and methods have been tested. In certain cultures the flagellate phase was prolonged for weeks or months. These cultures were characterized by: 1) great variation in size, from minute “dwarfs” to oversized “monsters”; 2) frequent multiple fission; 3) pairing and fusion, and, 4) some evidence for the origin of secondary nuclei from chromidia. In cases of pairing and fusion, the process of maturation and union of nuclei could not be definitely proved, although suggested by the observations.The flagellate phase is more probably the “adult” phase because of its complex organization and possible sexual phenomena. This case is considered an extreme for this type amoeba‐flagellate transformation.
The comparative morphology of the secondary sexual characters of elasmobranch fishes the claspers, clasper siphons, and clasper glands. Memoir VIII
Authors: Leigh‐Sharpe W. Harold 
Published: February 2005

AbstractChlamydoselachus resembles the Holocephali in possessing no siphon, but a cavity in the proximal portion of the clasper. The cartilages, musculature, and venous sinuses of the clasper are considered. An older specimen of Echinorhinus is proved to have a spine on a soft papilla; Scymnus has no spine; both have the general features of the Spinacidae. Two species of Cestracion are compared with C. philippi. Mustelus lunulatus lacks the pera and pseudosiphon of M. vulgaris. Dicerobatis has a peculiar scaphus, and the claspers end in a fimbriated manner. Pteroplatea resembles Trygon and Benthobatis and Astrape are both like Torpedo.The species are listed below.
The development of the thigh musculature of the chick twelve figures
Authors: Romer Alfred S. 
Published: February 2005

AbstractThe development of the thigh musculature in a series of chick embryos is described and figured. In the earliest the muscular tissue is in the form of two distinct masses lying on opposite surfaces of the limb. Later, both divide into proximal and distal portions at the knee. The proximal portions, by a series of divisions, gradually attain the condition found in the adult thigh.The embryological findings tend to support the theory of the derivation of tetrapod limb musculature from the two opposed (dorsal and ventral) muscle masses of the paired fins of bony fish.The reptilian homologies of the ilio‐trochanterici cannot be definitely ascertained from embryological evidence.The ischio‐femoralis (= ischio‐trochantericus), Previously regarded as dorsal, and the coccygeo‐femorales, previously classed as incertae sedis, are in reality members of the ventral group.The distinction between ‘intrinsic’ and ‘extrinsic’ muscles inserting on the free limb appears to have no embryological or phylogenetic basis in fact.Double innervation (motor) is a primitive condition in tetrapods.Rotation of the avian pubis is correlated with an improved functioning of the obturator in the rotated position coupled with a lack of interference with the other musculature concerned.
Ant‐mounds as to temperature and sunshine
Authors: Andrews E. A. 
Published: February 2005

AbstractThe ant Formica exsectoides F. builds mounds with some reference to sunlight, and measurements of internal temperatures have shown them higher in upper parts of the mound, but different in different faces of the mound—all higher than the earth outside the mound.Inside temperatures are not constant; they are due to the sunshine. The mound is so fabricated that the internal temperatures are conserved during the night. The ants make use of the differential internal temperatures for rearing broods.Some mounds show bilateral symmetry dependent upon sun exposure.Measurements of rate of running of these ants show a falling off with lower temperatures, and possibly this is one factor in the smaller development of northerly aspects of these mounds.
Oogenesis in Limulus polyphemus, with especial reference to the behavior of the nucleolus
Authors: Gardiner Mary S. 
Published: February 2005

AbstractA description is given of the cytoplasmic alterations in the ovarian egg of Limulus polyphemus leading to the formation of yolk. The nucleolus is found to arise by the confluence of substance which passes from the cytosome into the nucleus, and it is suggested that the chondriosomes, and possibly also the dictyosomes, are derived from an excess of this substance which accumulates in the cytosome. Chondriosomes and dictyosomes are not present in the oogonia, but appear first in oocytes after the formation of the nucleolus is completed.During oogenesis the nucleolus is very active and the greater part of its substance is passed back to the cytosome. By the application of the method of Bell and Doisy for the determination of phosphate in body fluids, the nucleolus is found to be richer in phosphorus than are the other constituents of the cell. The nucleolar emissions effect the transport of phosphorus from the nucleus to the cytosome, where it is used in the synthesis of yolk. The definitive yolk arises by the interaction of nucleolar emissions, chondriosomes, dictyosomes, and ground cytoplasm.
Conjugation in the ciliate Metopus sigmoides C. and L
Authors: Noland Lowell E. 
Published: February 2005

AbstractConjugating individuals of Metopus sigmoides fuse at the anterior end, the pair presenting the appearance of an inverted letter U. The micronucleus of each conjugant by two successive divisions forms four micronuclei. Three of each four degenerate and the fourth by division forms the pronuclei. Cytoplasm and pronuclei from one conjugant pass over into the other, leaving the old macronucleus and a minimum of cytoplasm behind in the shrunken pellicle of the smaller conjugant, which then separates from the larger one. In the larger exconjugant two pronuclei fuse, forming the functional synkaryon; the two residual pronuclei degenerate and disappear. The synkaryon divides. One of the daughter nuclei condenses into the new micronucleus, the other grows into the new macronucleus. The old macronucleus liquefies and is absorbed. The larger exconjugant, after losing its cilia, secretes a cyst wall about itself and becomes dormant. The whole process requires at least six days for its consummation.
Spermatogenesis in the Belostomatidae. II. The chromosomes and cytoplasmic inclusions in the male germ cells of Belostoma flumineum Say, Lethocerus americanus Leidy, and Benacus griseus Say
Authors: Chickering A. M. 
Published: February 2005

AbstractThis paper contains a description of the appearance and behavior of the chromatin and chief cytoplasmic inclusions in the male germ cells of three species of Belostomatidae.There are eight spermatogonial chromosomes in Lethocerus americanus, twenty‐four in Belostoma flumineum, twenty‐eight in Benacus griseus. An XY‐pair of sex chromosomes occurs in each species. These are identifiable at every step in maturation in Lethocerus, but not in the others. A clear case of heteropycnosis occurs in Benacus. Parasynapsis is believed to be the mode of pairing of chromosomes in all three species. The genesis of three large atelomitic ring tetrads is described in Lethocerus.Chondriosomes are traced from spermatogonia to spermatids without a break in continuity. Spermatogonial chondriosomes are always granular. During the growth period filaments are formed, probably by fusion of granules, and these are sorted out in approximately equal numbers to spermatids. Benacus is especially favorable for studies on chondriosomes. Likewise, Golgi bodies have been traced throughout the process of maturation. They are minute granules in spermatogonia. During the growth period each becomes a flattened plate‐like body clearly differentiated into two materials. Dictyosomes are formed by fragmentation in the first prophase, and these are distributed to spermatids where they fuse to form an acroblast in each. Some minor cytoplasmic inclusions are briefly described.
Trends in evolution: A discussion of data bearing upon ‘orthogenesis’
Authors: Metcalf Maynard M. 
Published: February 2005

AbstractFive characters–flatness, elongation, posterior pointedness, delay in division of the body, delay in completion of mitosis–are so distributed among the subdivisions of the Opalinidae as to involve either repeated fortuitous appearances of these characters, a thing not to be believed, or trends resident in the germ plasm. The Ophryoscolecidae show similar distribution of two sets of characters. In the Salpidae there is evidence of trends toward: coiling of the gut; decrease in number, size, regularity, and symmetry of body muscles; simplification and degeneration of the eyes. These qualities appear first in the phylogeny in the chain Salpas, the final phase in the life‐cycle. In the course of the evolution the solitary Salpas become more and more modified in the same directions, until, in the most highly modified species, the muscles and eyes are as much modified in the solitary Salpas as in the aggregated. These changes, not disadvantageous but rather adaptive in their beginning in the colonial individuals, are harmful to the solitary Salpas, yet the degeneration is, by precocious development, thrown back onto the earlier phase of the life‐cycle, the solitary stage. Precocious development is not purely utilitarian, but may be more fundamental, biological.Evolution is discussed in terms of trends resident in the germ plasm, their origin in connection with mutations, their growth, decrease, disappearance, branching; auto‐evolution. Discussion is from the standpoint of the germinal stream, internal factors of evolution being emphasized.
A study of the chromosomes in meiosis, fertilization, and cleavage in the grasshopper egg (orthoptera)
Authors: McNabb Josephine Willis 
Published: February 2005

AbstractA technique is developed whereby the large heavily yolk‐laden grasshopper egg may be sectioned for cytological study. Eggs of Chortophaga viridifasciata and Circotettix verruculatus were examined.In C. viridifasciata the structure of the late ovarian nucleus and the chromosomes in meiosis, fertilization, and early cleavage are described. In the first maturation twelve rod‐shaped tetrads are found. Near the caudal end of the egg a polar body is given off, and in the second maturation division there are twelve dyads. At fertilization, twelve separated vesicles of the female pronucleus are seen scattered about a male pronucleus in which the chromosomes are in prophase.In early cleavage the chromosome numbers in the metaphase are found to differentiate the male‐ and female‐producing eggs. In the former there are twenty‐three and in the latter twenty‐four chromosomes. A vesicular condition in which the chromosomes retain their boundaries in interkinesis is indicative of chromosome individuality.A comparison of the first and second maturation metaphase chromosomes of the oocyte with those of the spermatocyte shows a similar compact group on the spindle, a likeness in size seriation, and a similarity of form. They differ in that in the spermatocyte complex there are eleven tetrads and one dyad. This latter, the unpaired sex chromosome, falls among the large chromosomes.A comparison of the chromosome complex of Chortophaga viridifasciata with that of Circotettix verruculatus indicates constancy of generic differences in form, size, number, and behavior of the chromosomes.