Contributions from the Zoölogical Laboratory of the Museum of Comparative Zoölogy at Harvard College, Issues 91-100The Museum, 1808 |
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acid animal appeared brain budding zone cavity centrosome chitinous Collembola connected corpus luteum cytoplasm described diameter differentiated dorsal E. L. MARK ectoderm eight-tentacled elongated embryo en'drm fibres of set Figure follicle cells follicular formed ganglion cells germinative epithelium germinative vesicle giant fibres glands glossa granules hæmatoxylin halves head Heft hypodermis hypostome inserted kalymmocytes labium lateral layer lobe lumen mandible margin mass maxilla mean number median plane membrane mesoderm methyl green mouth-parts muscle band Nereis nerve cord nervous neurites neuroglia neuropil nuclei nucleolus number of tentacles oögonia oral tentacles organs origin ovary oviduct ovum pair paraglossa parapodial parapodium passes peribranchial sac peripheral pharynx pigment Plate portion posterior zoöid pouch regeneration region rhabdome seen segmental nerve separated seven-tentacled side six-tentacled Hydras species stage stain stalk tissue structure surface tacles Tentakeln tentorium test cells Transverse section tube vacuoles wall yolk bodies Zool
Popular passages
Page 122 - On the Presence of Centrosomes and Attraction Spheres in the Ganglion Cells of Helix Pomatia, with Remarks upon the Structure of the Cell Body. Princeton Coll. Bull., Vol. 8, No. 2, pp. 38-41.
Page 116 - FIG. II. or a decrease in the number of segments in front of the budding zone as compared with the condition in the parent. This variability is perhaps correlated with the rate of growth as dependent upon food, etc. It will be seen from the accompanying diagram (Figures I. and II.) that the half-segment A, 3 (Fig. I.) produces A, 3-7 (Fig. II.), which simulates the condition of A, 3-7 (Fig. I.), and consequently that the second new individual, which is thus to be produced at the posterior end of...
Page 99 - ... this account also he missed the entire process of the transformation of the cytoplasmic reticulum into yolk, which occurs at the same period. That this shrivelling of the germinative vesicle is closely associated with the formation of the yolk , is suggested by the synchronism of the two events, and it is interesting to note that the intense activity of the nucleus, of which this shrinking is probably the result, begins shortly after degenerative changes have commenced in the test cells. It seems,...
Page 137 - Vol. 20, pp. 88-106, Plates 1-3. Rievel, H. von. '96. Ueber die Regeneration des Vorderdarmes und Enddarmes bei einigen Anneliden. Zeitschr. f. wiss. Zool., Bd. 62, pp. 289-341, Taf. 12-14. Schultze, M. '49. Ueber die Fortpflanzung durch Theilung bei Nais proboscidea. Arch. f. Naturg., Jahrg. 15, Bd.
Page 210 - Labyrinth. Von Prof. Dr. F. Siebenmann in Basel. Mit 66 teilweise farbigen Abbildungen im Text. Preis für Abnehmer des ganzen Werkes: 7 Mark, Einzelpreis: 9 Mark.
Page 198 - ... fairly uniform diameter of from 0.5 mm. to 1 mm. The forking may extend to the production of branches of the ninth or tenth order. The terminal branches, of which there may be nearly 500 to a gill, end blindly with rounded tips. In alcoholic material the branches are often varicose, owing to distention with coagulated contents. In the living condition they are probably of much more nearly uniform calibre. When not contracted the gills rise above the oral orifice, and even above the oral tentacles...
Page 95 - ... of the structure increasing with the size of the vesicle, and culminating in the condition shown in Figure 48 (Plate 6). In addition to the reticulum, many isolated granules are found throughout the vesicle and especially on its membrane. While all these granules when stained with iron haematoxylin are very deeply colored, and resemble closely the chromatic structures described for other eggs, still, strictly speaking, we are not justified in calling them chromatin; for chromatin is that substance...
Page 99 - ... group, and in addition a very striking one of their own. The nucleus lies in the narrow end of the cell, and is surrounded by the granular cytoplasm. At the other end of the cell, there is a large vacuolar space containing a number of deeply staining bodies of irregular form, embedded in an indistinct coagulum. Other cells have very finely granular substance occupying a similar position, the granules being much smaller and staining less deeply than those of the body of the celL In these cases...
Page 53 - It turns out, however, on examination of sections from other individuals that these are really sexual organs. It results from all of these errors of mine that I have needlessly burdened the literature of Zoology with a new name, which no one can regret more than I, though I believe that the description given is fairly accurate as far as it goes. It is clear from what I have said that the animal in question must be more nearly related to the Hydroidea than to the Actinia, though its exact affinities...
Page 20 - The lacinia, or inner lobe (Fig. 31, le; 32, the same enlarged), in Tomocerus consists of two bundles of spinules, one broad like a ruffle, and the other slender, pencil-like, ending in an inner row of spines, like the spinules on the lacinia of the Japyx and Campodea...