bluuebunny/crossref_metadata_2025_split huggingface dataset:
The intranuclear deutoplsm and the origin of gametes in the turbellarian Prorhynchus applanatus Kennel
Authors: Jones E. Ruffin 
Published: February 2005

AbstractIt is shown that in Prorhynchus applanatus there exists a type of yolk elaboration which has hitherto not been reported. Formation is within the nucleus through the growth and fusion of nucleoli, but the yolk globule becomes larger than the original nucleolus. The developing individual utilizes the food material contained in the yolk cells in the following order: (1) cytoplasm of the yolk cell, (2) yolk bodies contained in this cytoplasm, (3) intranuclear yolk, (4) nucleoplasm. It is also shown that the germ cells in this form arise from the endoderm by diapedesis, but that the yolk cells are mesenchymal in origin. The sequence of formation of male and female gametes precludes the possibility of the presence of sex hormones such as are found in higher forms.
Vertebrate cephalogenesis. VI. A. The velum—its in head building—the hyoid. The Velata. The origin of the vertebrate head skeleton. B. Myxinoid characters inherited by the teleostomi
Authors: Ayers Howard 
Published: February 2005

AbstractThe oldest parts of the fibrous, cartilaginous, and bony head skeleton of vertebrates descend from the amphioxid ancestors of the myxinoid fishes. The skeleton of the velum and jaw bars of the amphioxids transform into the jaw apparatus and hyoid‐velar head skeleton of the myxinoids, and some parts are passed on by inheritance to the teleostome fishes (sturgeons). These anatomical characters prove descent with modification. The theory of the origin of jaws and hyoid from branchial cartilages is not supported by the facts, as both jaws and hyoid structures were developed long before branchial cartilages furnished material for head building. The Velata, the oldest of living vertebrates, include the amphioxids and marsipobranchs, and are marked off from the higher forms by the important organ, the velum, which separates the prebranchial from the branchial head. A remnant of the velum inherited by all of the higher vertebrates is the hyoid mechanism—an important anatomical landmark.
Polymorphism among the subgenera of nasutitermes
Authors: Hare L. 
Published: February 2005

AbstractThis study is concerned with the interrelationship existing among the polymorphie soldier castes of six representative subgenera of the genus Nasutitermes. By measurements of anatomical parts and camera‐lucida drawings, an attempt has been made to compare these particular subgenera on a basis of gradual divergence of certain structures. For this purpose a series of tables was compiled in which apparently unstable structures were compared to a relatively stable figure in all available species of the selected subgenera.According to my findings, it was concluded that there is no strict correspondence between the major, intermediate, and minor castes of different subgenera of the genus Nasutitermes. Particular reference is made to the work of N. Holmgren ('12) and to that of J. S. Huxley on heterogonic growth.
The histology of posterior regeneration in the polychaete Chaetopterus variopedatus
Authors: Faulkner G. H. 
Published: February 2005

AbstractAfter amputation, the wound is closed by the protrusion and lateral expansion of the alimentary canal over the cut muscles and its final fusion with the epidermis laterally after about twenty‐four hours. Associated with the expansion is a divergence of the two adjacent halves of the ventral nerve cord in the last remaining segment. As a result, the whole of the new regenerated lobe behind the ring of the cut epidermis is interneural; i.e., it is an enlargement of the normally small area separating the two nerve cords. Undifferentiated cells, or neuroblasts, are normally located interneurally, and during regeneration these neoblasts proliferate throughout the enlarged interneural zone of the papilla and migrate throughout the lobe. At first the neoblastic mesenchyme filling the lobe is loose and homogeneous, but as the cells settle down against the outer wall they replace the old intestinal cells and assume the characters of new epidermis. Internally, the mass acquires paired cavities, while the cells surrounding the cavities differentiate into muscle, peritoneum, etc. Thus one type of cell gives rise to the whole of the regenerated papilla. These cells are also the mother cells of the gametocytes.
The chondrocranium of a 23‐mm. necturus
Authors: Shumway Waldo , Webb Richard L. 
Published: February 2005

AbstractThis study is based on a wax model reconstructed from serial sections stained with basic fuchsin and picro‐indigo‐carmine. It shows: 1) that the columna ethmoidalis and planum basale are chondrified at this stage; 2) that a cartilaginous antorbital process is present; 3) that the stapedial plate is cut out from the wall of the otic capsule; 4) that the so‐called crista trabecularis is an independent element homologous with the sphenolateralis of the Anura; 5) that the fourth visceral arch is not present and that the fifth is still in the precartilaginous stage; and, 7) that there is no evidence that a pro‐occipital vertebra is formed.
Observations on the life history of a fingernail shell of the genus Sphaerium
Authors: Foster Thural Dale 
Published: February 2005

AbstractBy statistical analysis and microscopical examination of a series of monthly quantitative collections, an attempt has been made to interpret the life history and reproductive habits of Sphaerium solidulum, one of the numerous species of the genus Sphaerium.Individuals of the species under observation have a distinctly limited life span of approximately one year. The period of maximum reproduction of this species does not occur in the summer months, as previously believed, but in the winter months. Seasonal growth rings are not present on this shell, although concentric lines are characteristic. No individuals of maximum size were present during the months from August to February. Maximum‐size adults are apparently sterile. The analysis of distribution curves of each quantitative sample indicates two size groups in each collection as shown by the bimodal character of each graph. Distribution curves of embryos feature the bimodal character of the young and adult. The conclusions are founded on data secured from twelve monthly collections made from the same habitat totaling 7022 individuals.
The development of the prechordal plate and mesoderm of amblystoma punctatum
Authors: Adelmann Howard B. 
Published: February 2005

AbstractThis paper describes the development of the prechordal plate and mesoderm of Amblystoma punctatum from the late yolk‐plug stage to the stage of about nineteen somites.In the earliest stage described the prechordal plate is embedded in the roof of the archenteron and flanked on both sides by prechordal mesoderm with which it is fused. The characteristics and limits of the prechordal plate and mesoderm are discussed and the fate of both traced. It is demonstrated that the mesodermal cores of the mandibular arches are probably largely derived from the prechordal mesoderm which flanks the prechordal plate. The prechordal plate is later separated out of the roof of the foregut in a caudocephalic direction, giving rise to a median mass of mesoderm which expands laterally independently of the mandibular portions of the prechordal mesoderm to give rise to head mesenchyme lying largely anterior to the level of the hyoid arch. The expansion of this mesoderm is followed in some detail.The boundary between prechordal and notochordal regions is placed at approximately the boundary between the mandibular and hyoid arches.The question of the interpretation of the prechordal region is briefly discussed.
The embryology of amphioxus
Authors: Conklin Edwin Grant 
Published: February 2005

AbstractAlthough the egg of Amphioxus is much more fluid and less stereotyped than that of Ascidians, the poles, axes, and localizations of formative materials are much the same in the two. The spermatozoon enters near the vegetative pole and a peripheral layer of granular cytoplasm flows to this pole and later forms a crescent around the posterior side parallel to the first cleavage amphiaster; this is the mesodermal crescent. On the anterior side a similar area later gives rise to the chorda‐neural crescent. Above these crescents is the ectodermal area, below them the endodermal area. The early cleavages divide these crescents and areas just as in Ascidians. The coeloblastula is at first spherical, but later flattens in the region of the mesodermal crescent; this flattening extends forward on the vegetative side to the chorda‐neural crescent, where the invagination is sharpest. The blastopore is at first triangular in outline, the dorsal lip being formed by the chorda‐neural crescent and the lateral lips by the mesodermal crescent. Later the chorda and the mesodermal crescents are infolded, the lateral lips fuse to form the ventral lip which grows dorsalward, the blastopore becomes wider from right to left than dorsoventrally, the gastrula elongates and in the angles between dorsal and ventral lips the mesodermal crescent forms the mesodermal grooves in the lateral walls of the gastrocoel.
Observations upon the American representative of macrostomum tuba
Authors: Kepner William A. , Stiff M. W. 
Published: February 2005

AbstractWhat appears to be a variety of Macrostomum tuba has been described in this paper. There is but a single retinula in each eye. This visual cell displays three regions: rhabdome, ellipsoid, and myoid, as does a vertebrate's retinula. Moreover, the accessory pigment associated with the retinula of M. tuba is applied to the rhabdome and not to the ellipsoid and myoid; this likewise is similar to the distribution of the pigment about the vertebrate's retinula. An analogy, therefore, may be drawn between the visual cell of the rhabdocoele and that of the vertebrate. This is so strong as to suggest homology. Several features peculiar to this variety are: first, the chitinous, distal ring of the penis; second, the fact that shell and yolk droplets seem to be elaborated by each cell destined to become an oocyte.
Comparative cytochemical studies by micro‐incineration of a saprozoic and an holozoic infusorian
Authors: Horning E. S. , Scott Gordon H. 
Published: February 2005

AbstractNyctotherus cordiformis and Opalinids infesting Rana pipiens were studied by microincineration and in stained control sections. A marked difference in concentration and distribution of mineral salts was noted within saprozoic and holozoic organisms. The endoplasm in the saprozoic protozoa was free from inorganic residue except for the ‘vegetative’ granules; the protoplasm of the holozoic infusorians consisted of a fine network of mineral salts. Detailed examinations suggested that the qualitative and quantitative differences might be correlated with diffusion of digestible material through the cuticle. The inorganic residue of the walls of vacuoles was relatively rich in iron.
Histology of the fresh‐water mussel heart with reference to its physiological reactions
Authors: Motley Hurley Lee 
Published: February 2005

AbstractThe anatomical isolation of the auricles from the ventricle in hearts of fresh‐water mussels representing nine North American species has been confirmed. The muscle fibers in these hearts without exceptions were found to be of the smooth, unstriated type. Bundles of these fibers loosely interwoven, form the thin, delicate, heart wall, which contains many sinus‐like spaces. The outside portion of the heart wall exposed to the pericardial fluid is covered with a definite epicardium composed of a single, dense layer of epithelial and scattering mucous cells. The inside of the heart cavity has no endocardium, the muscle fibers being in direct contact with the blood. No special conduction tissue, nerves or ganglia were found in the heart wall. Correlations of these anatomical and histological findings with the physiological reactions of the living heart in situ are made, and the mechanical and chemical control of the heart discussed.
Sex cycles and other cyclic phenomena in a chimpanzee during adolescence, maturity, and pregnancy
Authors: Tinklepaugh O. L. 
Published: February 2005

AbstractThe sex cycles of a chimpanzee were studied for 18 months, during which the animal matured, menstruated four times, conceived, and delivered.Pronounced swelling of the ano‐genital region appeared periodically prior to the first menstruation. During menstrual cycles the swelling endured during most of the period between flows. Genital swelling was always accompanied by estrus; copulation and insemination never occurred during its absence.The animal was alert and active when in estrus, demonstrated non‐sexual affection for the male just prior to the flow, and appeared to be physically distressed during the first days of each flow.There were periodic weight changes coordinated with the animal's menstrual cycles.During pregnancy menstruation ceased, but genital swelling, with accompanying sexual receptivity, continued in irregular cycles.Cyclic changes in the desquamation of the vaginal epithelium occurred during menstrual cycles, were absent during pregnancy.The gestation period was approximately 246 days. At death from puerperal sepsis, 15 days after delivery, the ovaries were in a restin stage, one of them bearing a degenerating corpus luteum.The evidence given indicates that sex‐skin swelling and estrus are similarly controlled, but may occur independently of menstruation, cornification of the vaginal epithelium, or ovulation.
Studies in living tissue
Authors: Baumgartner W. J. 
Published: February 2005

AbstractA survey of biological literature of the present reveals a tendency to turn to the study of the living cells and tissues. This tendency is indicated by the use of microdissection, ultraviolet microscopes, transparent chambers in rabbits' ears, growing nerve cells and fibers in tailfins of amphibian larvae, and by intravitam technic on insect germ cells. The division stages of the germ cells of Anasa tristis which were carefully studied and drawn thirty‐odd years ago are now shown by actual unretouched photomicrographs. These photomicrographs confirm the drawings in many points and show other structures such as mitochondria even more clearly than the drawings do. An account of a peculiarly shaped spermatozoon which has not been described heretofore in the literature is added. The question of the great variations of shapes of spermatozoa is discussed. The advantages of the use of methods for studying living cells, especially of intravitam technic, is emphasized.
The effects of bilateral and unilateral castration on the epididymis, with special reference to the mitochondria‐Golgi complex
Authors: Winters Laurence M. 
Published: February 2005

AbstractRats in different stages of maturity were castrated in pairs–bilaterally and unilaterally–with respect to the effects upon the epipidymis. The epididymis was also studied during its developmental stages. A special study was made of the mitochondria and Golgi materials; and a comprehensive review of the literature is included.Bilateral castration was followed by a marked regression of functional activity on the part of the epithelial cells of the epididymis. Unilateral castration produced no similar change. The mitochondria‐Golgi complex in the epithelial cells of the epididymis was reduced decidedly following bilateral castration; while unilateral castration had no visible effect upon these materials. The mitochondria‐Golgi complex increased and decreased in amounts in keeping with the state of secretory activity of the epithelial cells.Golgi nets were found within the lumina of the tubules. Granules within the cells and the tubules were colored with osmic acid, Altmann's anilin acid‐fuchsin, iron hematoxylin, or acid fuchsin‐orange G. Osmic acid impregnation was removed from granules and nets and Altmann's anilin acid‐fuchsin stain put in its place.It is believed that mitochondria and Golgi materials are very similar and furthermore that they are secretory products of the cells. It is also believed that the state of development of the mitochondria‐Golgi complex is an indication of the functional state of the epithelial cells of the epididymis.
Studies on the spermatocyte divisions in ascaris megalocephala; with special reference to the central bodies, Golgi complex and mitochondria
Authors: Sturdivant H. P. 
Published: February 2005

AbstractThe centrioles are recognized early in the prophase of the primary spermatocyte. They soon become double and migrate around the nucleus in opposite directions. As this is completed the nuclear membrane breaks down and spindle fibers appear. The centrioles divide in the metaphase at a time when the centrosome is still perfectly spherical. The centrosome divides in the anaphase, giving the two centers for the second division. The centriole disappears in the spermatid and cannot be seen in later stages. The behavior of the centers during the spermatocyte divisions is strikingly like that of the egg centers and other types of mitoses. Therefore, it is concluded that the centrioles of the spermatocytes are not to be regarded as different from the centrioles in other types of mitoses.The Golgi bodies increase in number and size during the growth period of the cell. They are usually found in the shape of rings. From these rings are produced the refringent granules which fuse in the late spermatid to form those of the mature sperm. It is therefore concluded that this process represents the formation of the acrosome. The mitochondria show little change during the maturation divisions. In the late spermatid they aggregate around the nucleus and become vesiculated. This is interpreted as the formation of the prenebenkern.
The segregation of the germ cells in the grasshopper, Melanoplus differentialis (acrididae; orthoptera)
Authors: Nelsen Olin E. 
Published: February 2005

AbstractThe segregation of the germ cells is related in time and differentiation to the ectoderm (ventral plate), the inner germ‐band layer (lower layer) and the mesenteron (entoderm) rudiments. The inner germ‐band layer is formed by invagination of cells from a median blastoporic groove and by cellular proliferations among the invaginating cells and from the median line of the ectoderm immediately caudad of the blastoporic groove. The mesenteron material is derived from inner germ‐band layer material associated with the internal ends of the stomodaeum and proctodaeum. The germ cells are segregated from the lateral margins of the abdominal lobe ectoderm in the region of the amnion attachment as segmentation of the abdominal lobe is initiated. They ultimately become separated from the ectoderm cells of the lateral wall and from the amnion and migrate in a passive manner onto the coelomic sacs where they become associated with the inner walls of the sacs. When the coelomic sacs unite the germ cells and the splanchnic wall mesoderm cells form two continuous cell strands from the first to the eighth abdominal segments, inclusive. These strands form the indifferent genital rudiments. An endeavor is made to correlate the segregation of the germ cells in the grasshopper with that of various other insects.
The distribution of chitin in an insect
Authors: Tauber Oscar E. 
Published: February 2005

AbstractBy treating the clean skeletal tissue of an insect with concentrated KOH at 160° C., the contained chitin is converted to chitosan, and all pigmentation and admixtures are removed. The per cent distribution of chitin, expressed as chitosan, in the exoskeleton of the cockroach, Periplaneta fuliginosa, ranges from 37.65 in the dorsal abdomen to 18.22 in the hindwings. Other regions contain the following per cents: ventral abdomen, 37.11; metathoracic legs, 35.55; mesothoracic legs, 33.28; prothoracic legs, 32.24; pronotum, 31.55; head, 31.07; genitalia, 29.28; dorsal thorax, 29.07; ventral thorax, 28.33; antennae, 27.77; cerci, 25.65; and forewings, 19.99. Regional variations are constant in different individuals of the same species. The crop and gizzard contain 18.69 per cent; the hindgut, 18.15 per cent. The remainder of the alimentary tract contains no chitin. Traces of chitin are found in the trachea. No chitin is found in the egg‐cases of this species. No correlation between chitin content and pigmentation or hardness is shown. Based on results from three trials, using thirty insects, the per cent of chitosan in the clean, dry chitinous material from the entire animal is 29.60; the per cent of chitosan based on the weight of the live animal averages 2.01.
Localization of mineral ash in the organelles of trichonympha, a hypermastigote flagellate from zootermopsis angusticollis
Authors: Maclennan R. F. , Murer H. K. 
Published: February 2005

AbstractThe three species of Trichonympha found in Zootermopsis angusticollis were studied by micro‐incineration, by control sections, and by Macallum's methods for iron and calcium. The mineral ash is concentrated in the neuromotor system, chromatin, nuclear membrane, the posterior end where ingestion takes place, and in cytoplasmic granules. Micro‐incineration and Macallum's Prussian blue method reveal iron in the chromatin alone; Macallum's haematoxylin gives a positive test for iron in the chromatin, rostrum, neuromotor fibrils, etc. It probably is not as specific as the other methods. The two staining methods give negative tests for iron except after acid hydrolysis. Calcium is present in the chromatin, neuromotor system, posterior region of the body, and in many endoplasmic granules. The localization of calcium is correlated with the localization of normally gelated regions.
Caste determination and differentiation with special reference to the genus reticulitermes (Isoptera)
Authors: Hare Laura 
Published: February 2005

AbstractThe results of recent investigations concerning caste determination among termites have been briefly reviewed with emphasis upon the work of Thompson ('17). From examination of new data upon the development of Reticulitermes arenincola Goellner, R. flavipes (Kollar), and R. tibialis Banks, and of Thompson's original R. flavipes material, I am unable to substantiate her claim that the sterile and reproductive castes are separable into two distinct groups at the time of hatching. I could distinguish them first in stadium three and suggest that the second stadium may be a critical period in differentiation. From evidence to date, it must be granted that both intrinsic and extrinsic factors may play a role in the production of castes. The delay in appearance of demonstrable caste differences until the third stadium in the genus Reticulitermes at least admits of an opportunity for extrinsic factors to be effective. Growth and metamorphosis of various structures which ultimately lead to the three differentiated castes have been followed through successive stadia. Gynandromorphs and intercastes among social insects give indication of the physiological and genetic factors influencing both morphological and behavior differences among castes.