The cell in development and inheritance . anchs. It has since been described by Meves(97, 2) and Hermann (97) in the salamander, by Lenhossek (97), Meves (98, 99), andBardeleben (97) in the rat, guinea-pig, and man; by Godlewski (97) and Korff (99) inHelix, and by several others. - Calkinss preparations, which I have carefully examined, seem to leave no doubt that themiddle-piece arises from a true attraction-sphere derived from the spindle-poles; butErlanger believes that the granular centrodeutoplasm also contributes to the sphere. 166 THE GERM-CELLS consisting of three parts, lying side by
The cell in development and inheritance . anchs. It has since been described by Meves(97, 2) and Hermann (97) in the salamander, by Lenhossek (97), Meves (98, 99), andBardeleben (97) in the rat, guinea-pig, and man; by Godlewski (97) and Korff (99) inHelix, and by several others. - Calkinss preparations, which I have carefully examined, seem to leave no doubt that themiddle-piece arises from a true attraction-sphere derived from the spindle-poles; butErlanger believes that the granular centrodeutoplasm also contributes to the sphere. 166 THE GERM-CELLS consisting of three parts, lying side by side in the cytoplasm (Fig. 83).These are {a) a colourless sphere, shown by Mevess later researches tobe probably an attraction-sphere; (^) a minute, intensely staining cor-puscle, and {c) a small, deeply staining ring. The concurrent resultsof Hermann (89, 92, 97), Benda (93), and Meves (96, 97, 2) haveshown that the small corpuscle {c) is one of the centrosomes of thespermatid, and all these observers agree that it passes into or gives. Fig. 84. — Formation of the spermatozoon in Amphibia. \^A-E. Salammidra, Meves;F-K. Amphimna, McGregOR.] A. Spermatid with peripheral pair of centrosomes lying outside the sphere, and axial Centrosomes near the nucleus, outer one ring-shaped. C. Inner centrosome inside thenucleus, enlarging to form middle-piece. D. Portion of much older spermatid, showing divergenceof two halves of the ring (r). E. Portion of mature spermatozoon, showing upper half of ring atr, and the axial filament proceeding from it. F. Spermatid of Amphiuma, showing sphere-bridges and ring-shaped mid-bodies. G. Laterstage; outer centrosome ring-shaped, inner one double; sphere {s) converted into the Migration of the centrosomes. /. Middle-piece at base of nucleus, y. The inner centrosomeforms the end-knob within the middle-piece, which is now inside the nucleus. K. Enlargement ofmiddle-piece, end-knob within it; elongation of the ring. GROWTH AND
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectcells, bookyear1902
