bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Ciliary Mechanisms and Interrelationships of Lamellibranchs: PART II: Sorting Devices on the Gills
Authors: Atkins Daphne 
Published: April 2021

ABSTRACT
Some sorting devices on the gills of Lamellibranchs are described. These are: Utilization of plicae for sorting in two ways; the one (a) in which the frontal currents are in opposite directions in the grooves and on the crests, and particles intended for consumption are carried in the grooves to the safe dorsal channels, e.g. in Pecten; and the other (b) in which the plical grooves open into the safe channel at the bottom of the deep marginal food groove, while the crests lead to a superficial path along the lobes of the marginal groove, e.g. in Pinna.The deep marginal groove of the demibranchs of certain bivalves is able to open and close, thus accepting or rejecting material carried to it by the frontal cilia of the filaments, e.g. Solecurtus scopula.Certain Lamellibranchs have fan-shaped groups of long cilia on the lobes of the marginal groove of the demibranchs, which prevent the entry of large particles or collections of particles, but allow that of small ones, e.g. Musculus marmoratus.In certain bivalves long, stout frontal cilia are found in addition to the usual short, fine ones. The cirrus-like cilia most probably function in the removal of grains of sand and rock from the gills, e.g. Mactra corallina, Barnea parva.
Small gills and large palps are characteristic of certain deposit feeding bivalves with long free siphons, and the presence of large, cirrus-like cilia on the posterior region of the gills beating obliquely forward, provide additional help to draw the current down the long inhalent siphon.
Certain of the ciliary structures described in this paper are clearly adaptive, correlated with feeding difficulties incidental to the habitat. Fine guarding cilia appear to be frequently correlated with the presence of a certain amount of mud or silt in the soil; they are presumably efficient in dealing with the particles of a muddy soil, but not sufficiently robust when mainly coarse material has to be dealt with. A correlation of cirrus-like cilia with sand dwelling and rock and wood boring habits has been observed.
It will be evident from the observations recorded in this paper that a preliminary sorting of material on the gills before it is passed on to the palps is far from unusual in Lamellibranchs. Further research will most probably add other examples.
On the Ciliary Mechanisms and Interrelationships of Lamellibranchs: PART III: Types of Lamellibranch Gills and their Food Currents
Authors: Atkins Daphne 
Published: April 2021

ABSTRACT
Seven main types of Lamellibranch gills and their food currents, together with a number of varieties, have been described. These are shown summarily and comprehensively in the composite diagram in Text-fig. 18.
The Structure and Development of the Tail in the Plaice (Pleuronectos Platessa) and the Cod (Gadus Morrhua)
Authors: Barrington E. J. W. 
Published: April 2021

ABSTRACTThe structure and development of the tails of Pleuronectes platessa L. and of Gadus morrhua L. are described, with some reference to Gadus merlangus L. In Pleuronectes: (a) seven hypural cartilages are identified, the most posterior becoming a dorsal element in the definitive tail while the next three fuse to form the upper of the two hypural bones borne by the terminal vertebra; (b) the penultimate vertebra comes to bear two dorsal and two ventral arches, probably basalia, as a result of their fusion during development; (c) the last neural and haemal arch bear traces of transient interbasalia at their first appearance. In Gadus: (a) the tail resembles that of Pleuronectes in certain respects, including the general arrangement of the dorsal and ventral skeletal elements, the appearance of transient interbasalia in connexion with the last neural and haemal arch, and the fusion of two dorsal and ventral arches, although these come to be borne by the ante-penultimate vertebra instead of by the penultimate vertebra; (b) the embryonic axial lobe of the fin is median (instead of dorsal as it is in Pleuronectes) as a result of the upper half of the definitive fin being formed by the backgrowth of a dorsal fin-fold. The two types of fin are compared, and it is concluded that the Gadoid fin could have been derived by the fusion of a homocercal fin, of a type more primitive than that of Pleuronectes, with a dorsal and ventral fin-fold, accompanied by the loss of the most terminal of the hypurals characteristic of the normal homocercal fin.
The Effects of Ultra-centrifuging the Oocytes of Lumbricus terrestris
Authors: Norminton Gertrude M. 
Published: April 2021

ABSTRACT
The ultra-centrifuged cell becomes stratified into fourlayers: fat, cytoplasm containing the nucleus and Golgi bodies, mitochondria, and a clear substance. The fairly large spherical, greyish bodies seen in the living oocytes of Lumbricus are fat, not Golgi bodies. This fat contains cholesterol. The Golgi bodies are slightly curved, or straight rods, found, in the ultra-centrifuged cell, in a layer placed centrifugally to the nucleus. The neutral-red granules are artifacts. If centrifuged they collect beside and beyond the nucleus. The mitochondria are granular and may become alined into chains. The heaviest substance in the cell is probably a fluid.
On the Histology of the Skin of the Lungfish Protopterus annectens after experimentally induced Aestivation
Authors: Smith G. M. , Coates G. W. 
Published: April 2021

ABSTRACT
During the past year observations have been made on the histological structure of the skin of two lungfishes (Protopterus annectens Owen) kept for a period of almost six months under conditions of aestivation induced experimentally at the New York Aquarium. Both lungfishes had been caught in the fresh-water marshes near Beira, East Africa, and shipped directly to New York. They were adult fishes and measured approximately 14 inches in length.
On the Protozoan Parasites of Calanus finmarchicus in the Clyde Sea Area
Authors: Jepps Margaret W. 
Published: April 2021

ABSTRACT
An account is given of the parasites reputed to be of protozoan nature which were observed in Calanus finmarchicus in the Clyde Sea Area, during the years 1933 to 1936. These comprise Blastodinium, Syndinium, some Gregarines, an ectoparasitic Ciliate new to science, Paradinium, Ellobiopsis, and Ichthyosporidium, besides early stages in the development of some Platyhelminth worms.
A special study is made of Paradinium, which was plentiful throughout the summer months, and of the effect of the plasmodial parasites on their hosts.
Remarks on the New Nineteen-Band Test-Plate of Nobert
Authors: Woodward J. J. 
Published: April 2021

ABSTRACT
In comparing the various object-glasses belonging to the microscopical section of the Army Medical Museum, the test plate of Nobert has been much employed recently as the most accurate means of determining defining power. The plate used was one of the nineteen-band plates most recently furnished by Nobert; and its use for the purpose indicated has led the writer to a somewhat detailed study of the plate itself.
The Structure and Development of Wax Glands of Pseudococcus maritimus (Homoptera, Coccidae)
Authors: Pollister Priscilla Frew 
Published: April 2021

ABSTRACT
The females of Pseudococcus maritimus have three types of multicellular wax-glands, one with a triangular external pore, another opening through a long tube, and a third with a multilocular aperture. The first two are widely distributed on all surfaces of the adult. The third is restricted to the ventral surfaces of the last five segments. This multilocular type is found only in the adult. The triangular glands are found at all stages and these structures progressively increase in number with each successive instar. The tubular type appears first in the second instar; the number is reduced in the third instar; and in the adult it is again increased to the largest number found at any stage.
The three glands are all modifications of one general plan of histological structure. The glandular elements are sub-epidermal cells arranged in a ring of peripheral cells surrounding a single central cell. There are three peripheral cells in the triangular gland and ten in each of the others. The peripheral cells are uninucleate and contain vacuoles of secretory material. The central cell of the tubular and triangular glands has a large and two small nuclei and contains a large reservoir, from which a chitinized duct system leads to the gland-pore. The central cell of the multilocular gland is small and relatively undifferentiated. The author favours the view of Šulc that the wax is probably secreted by the peripheral cells, while the central cell secretes a substance that causes the wax filaments to adhere to form large cylinders.
The glands are developed by cell-multiplication from the epidermis at the time when it is freed from the cuticula at the beginning of ecdysis. After the initial period of cell-multiplication the first differentiation is the development of the external pore within the neck-cell. Later in the development of multilocular glands it is believed the glandular cells grow through the neck-cell to establish the functional relationship with the pore. It is suggested that this is analogous to the relationship between tormogen cell and trichogen cell in the development of a spine.
On the Spinal Nerves of the Myxinoidea
Authors: Goodrich Edwin S. 
Published: April 2021

ABSTRACT
The spinal nerve in the Gnathostomata is of mixed function, being formed by the junction of a mainly sensory dorsal root, provided with a ganglion, with a ventral motor root. The mixed nerve passes outwards posteriorly to the myomere supplied by its ventral root. Intersegmental arteries run dorsally from the dorsal aorta between the successive myomeres, and each artery passes up posteriorly to the spinal nerve. Segmental nerves and intersegmental arteries therefore alternate. These fundamental relations, illustrated in Text-fig. 1, are constant from fish to man, and can be seen in embryonic stages (Goodrich, 1930); but they may be modified in the adult.
On the Ciliary Mechanisms and Interrelationship of Lamellibranchs: PART VI. The Pattern of the Lateral Ciliated Cells of the Gill Filaments of the Lamellibranchia
Authors: Atkins Daphne 
Published: April 2021

ABSTRACT
The pattern of the lateral ciliated cells of the gill filaments has been examined in a number of Lamellibranchs and figures given, In the Protobranchia the lateral ciliated cells, except for a row on the abfrontal side, have no definite shape or arrangement; in the higher Lamellibranchs there is an orderly arrangement of the approximately rhomboidal cells in rows. The arrangement of the cells in any species appears to be constant. In the group possessing micro-latero-frontal cilia the variation in the pattern of the lateral ciliated cells in the various families is in marked contrast with the constancy of the general type of pattern found in the majority of the Eulamellibranchs.
On the Anatomy of Cercaria Macrocerca from Sphaerium Corneum.
Authors: Vickers G. G. 
Published: April 2021

ABSTRACT
A detailed anatomical description is given of the sporocyst and cercaria of Cercaria macrocerca (Fit) from the gills of Sphaerium eorneum (Linn.).
The development of the large cells surrounding the excretory vesicle of the cercaria is described. It has been found that the granules with which these cells are packed originate round the nucleus and afterwards migrate towards the lumen of the vesicle. These granules do not appear to be discharged on encystment of the cercaria to act as cystogenous material ; they are shed gradually into the excretory vesicle, and it is therefore natural to suppose that they are granules of excretory material.
In heavy infestations the mechanical effect of large numbers of sporocysts between the gill lamellae of the host completely prevents reproduction of the mollusc. Cercariae escaping from the sporocysts continually rupture the gill lamellae of the host, and large areas of the gills are thus put out of action.
The Chromosomes of the Cymothoid Isopod Anilocra.
Authors: Callan H. G. 
Published: April 2021

ABSTRACT
Anilocra mediterránea has a diploid chromosome number of twelve, eight of the chromosomes having median, and four subterminal centromeres.
The localization of chiasmata is extreme and is of a previously undescribed type, combining the terminal and centric systems.
The centromeres stain differentially from the non-centric regions of the chromosomes ; they are the only parts stained at anaphase of first meiosis, and at metaphase and anaphase of second meiosis.
The Enteronephric Type of Nephridial System in the Genus Tonoscolex (Gates)
Authors: Bahl Karm Narayan 
Published: April 2021

ABSTRACT
The ‘enteronephric’ type of nephridial system, previously described by the author in Pheretima, Lampito, and Woodwardiella (Nellogaster), has now been shown to characterize the genus Tonoscolex as well. It seems that this type of excretory system is widely distributed in the subfamily Megascolecinae. The nephridia are of three kinds: the enteronephric septal nephridia, the exonephric integumentary nephridia, and the enteronephric pharyngeal nephridia. There are twenty-four to thirty séptal nephridia in each of those segments where they are best developed, these nephridia being much larger in size than the septal micronephridia of Pheretima. The pharyngeal nephridia form a cylindrical bunch around the oesophagus in the sixth segment and open into the pharynx in front by a large number of ducts. The integumentary nephridia are extremely minute and open singly on the body-wall. The elaborate system of septal excretory canals and supra-intestinal ducts characteristic of the septal nephridial systems of Pheretima, Lampito, and Woodwardiella, does not exist in Tonoscolex. The system in Tonoscolex is therefore much simpler and probably more primitive, and may represent an intermediate stage between the purely exonephric meganephridia ofLumbricus and the elaborate enteronephric system of Pheretima, Lampito, and Woodwardiella.
Cytology of Human Uterine Glands in Gravid and Non-Gravid Phases
Authors: Aykroyd Olive E. , Gatenby J. Brontë 
Published: April 2021

ABSTRACT
After menstruation the basalis regions of the uterine glands alone persist. The columnar cells evacuate most of their granular contents, and the Golgi apparatus loosens out and breaks up. (Text-fig. 3 A.) The postmenstrual cells are cubical limpid cells, with a Golgi apparatus consisting of a few granules arranged in a line. (Text-fig. 3 B.) In the proliferative phase the Golgi apparatus re-forms and grows into a characteristic net. The cells become columnar. No marked aggregation of granules has as yet occurred. In the progravid phase, the cells become cubical, the Golgi apparatus spreads, and a marked aggregation of fat and glycogen appears at the inner pole of each cell. (Text-fig. 3 C.) Should pregnancy supervene, the cells secrete numerous ovoid (proteid) granules at their outer poles (Text-fig. 3 D). These granules are topographically related to the outer edge of the Golgi apparatus. The presence of the granules in any specimen of curetting reveals that it has been recovered from a case of interrupted pregnancy. Exceptions to this might be those which are known to hold for the Ascheim-Zondek pregnancy test. The uterine glands contain only one type of secretory cell which may be ciliated or non-ciliated.
The Blood Systems of Sabella and Spirographis
Authors: Ewer D. W. 
Published: April 2021

ABSTRACT
The anatomy of the blood system of Sabella pavonina is described. Differences from Sabella found in the structure of the blood system of the closely related Spirographis spallanzanii are pointed out. Very young Spirographis show no difference in the structure of the blood system from Sabella. Certain of the differences are, however, found in slightly larger specimens of Spirographis which are smaller than fully grown Sabella. The differences are therefore regarded as specifically significant. A preliminary account is given of the histology of the blood-vessels. The main longitudinal vessels show a distinct muscular layer, which is absent in circular and capillary vessels. The course of the circulation is described. An explanation of the mechanism of the sorting of oxygenated and deoxygenated blood is put forward. Peristalsis in the main longitudinal vessels occasionally reverses its direction ; there is thus no physiological polarization of the direction of peristalsis. The occurrence of blind-ending vascular structures in other polychaetes is reviewed and suggestions put forward concerning their function.
A Study of the Cytoplasmic Inclusions during Maturation, Fertilization and the First Cleavage Division of the Egg of the Mouse
Authors: Gresson R. A. R. 
Published: April 2021

ABSTRACT
1. Ova of the mouse were fixed at times varying from 5 to 43 hours after copulation.
2. Ovulation may take place at either the stage of the first or the second maturation division.
3. The sperm enters the egg during the anaphase of the second maturation division. As indicated by one egg the sperm may occasionally enter during the first division. The second maturation division takes place between 5 to about 7 hours after pairing. The stage of the pronuclei may be reached at about 6 hours after pairing, but usually is not reached until later. The first cleavage division takes place between 21 and 28 hours.
4. During the maturation divisions the yolk-globules are most numerous in the half of the egg opposite to that at which the divisions are taking place. The mitochondria are granular and are collected into small clumps ; a few, chiefly towards the periphery, are scattered singly through the cytoplasm. They are most numerous in the central region. During the first division, and in the early stages of the second division, they are numerous around the spindle. Few mitochondria are eliminated in the polar bodies. The Golgi elements are in the form of granules and of small irregularly shaped bodies; they are fairly evenly distributed through the cytoplasm.
5. During the stage of the pronuclei the distribution of the yolk-globules is similar to that during the polar divisions. In the later phases there is a concentration of the mitochondria in the neighbourhood of the pronuclei. The Golgi elements are scattered through the cytoplasm; they increase in size and undergo fragmentation.
6. The mitochondria become arranged around the spindle of the first cleavage division and are transmitted with approximate equality between the first two blastomeres. The Golgi elements remain scattered through the cytoplasm but are slightly more numerous in the neighbourhood of the zygote nucleus. The Golgi elements and the yolk-globules are fairly evenly distributed between the first two blastomeres.
7. The middle-piece of the sperm is carried into the egg. The mitochondria of the sheath are, at first, larger than those of the egg ; they spread out through the cytoplasm and undergo fragmentation. It is concluded that the mitochondria of the sperm are transmitted to the first two blastomeres. There is evidence that the Golgi elements of the middle-piece fragment and that the individual elements become scattered through the ooplasm before the first cleavage division.
8. Granular mitochondria are present in the blastomeres of the two-cell stage ; they are collected into small clumps and are scattered singly through the cytoplasm. The Golgi elements undergo fragmentation; they are fairly evenly distributed throughout the cytoplasm.
Abdominal Appendages of Asellus, II
Authors: Needham A. E. 
Published: April 2021

ABSTRACT
1. The anterior abdominal appendages of A. meridianus, while showing fundamental similarity to those of A. aquaticus, show considerable differences in structure, function, and development.
2. Neither species shows a complete superiority over the other in respect of these differences, nor is there as yet reliable evidence from experiment or from observations on distribution as to their relative viability.
3. The evidence from development in sum indicates that the A. meridianus group is the more primitive, the A. aquaticus type recapitulating an A. meridianus stage. Both groups have, however, evolved considerably since their first divergence, the changes affecting all stages of ontogeny; in respect of one species difference in particular, A. meridianus shows overstepping of the A. aquaticus condition which is primitive.
4. In the male A. meridianus there is considerable functional transposition between parts of the system as compared with A. aquaticus.
5. The developmental studies indicate further: (1) the extreme regularity of the processes, even to the smallest detail ; (2) the independence of growth and development on periodicity in moulting; (3) methods of addition of setae during development.
6. In the light of these studies the female intersexes of Maercks (1931) are seen to correspond to stages in normal male ontogeny, but with asynchronizations between parts of the appendages.
7. The intersex of Unwin (1920) may have been a species hybrid. He was working with A. meridianus, rather than with A. aquaticus as he believed.
8. A case of compound heteromorphosis affecting the anterior abdominal appendages of A. meridianus is described, and the importance of the peripheral motor nerves in the determination of the phenomenon is indicated.
9. Regeneration in these appendages may be quite normal, when it shows an accelerated recapitulation of ontogeny. It may be abnormal in showing lack of synchronization between parts, or even complete suppression of some. The rate of regeneration increases with age up to a point, and then decreases. It also decreases with the amount of an appendage removed.
10. Relative independence and lack of synchronization between parts is thus seen in intersexes, in other abnormalities, and in regeneration, and in all cases may depend on peripheral motor nerves.
11. Chains of sense cells and hollow chitinous ingrowths associated with them are attached to the base of many of the setae in Asellus.
The ‘Dorsal Organ’ of Collembolan Embryos
Authors: Tiegs O. W. 
Published: April 2021

ABSTRACT
Our present knowledge of the problematical ‘dorsal organ’ of Collembolan embryos is based mainly on the writings of Uljanin (1875), Lemoine (1883), Wheeler (1893), Claypole (1898), Uzel (1898), and Philiptschenko (1912). Owing to the minute size of the embryos of most Collembola much difficulty has been experienced in making accurate observations on its structure ; only in the work of Claypole and of Philiptschenko have actual sections been employed for the purpose.
Ciliary Currents in the Mantle Cavity of the Atlantidae
Authors: Yonge C. M. 
Published: April 2021

ABSTRACT
The ciliary currents in the mantle cavity of the Heteropod, Oxygyrus, were examined in the intact animal. The presence of three sets of currents concerned with the rejection of sediment, already postulated from examination, after dissection, of the mantle cavity in other Prosobranchs, was confirmed. The great majority of the sediment brought in with the respiratory current impinges on the line of the osphradium. This favours the conclusion that this organ is tactile in function and not a chemoreceptor. The extent to which the organs and currents in the mantle cavity are modified as a result of pelagic life is discussed.