The cell in development and inheritance . rms through the independentand nearly simultaneous researches of myself on the ^^g of Toxo-pneustes, of Mathews on Ajbacia, and of Boveri on Echinus. Nearlyat the same time a careful study was made by Mead (95, 98, i) ofthe annelid ChcBtopterics^ and of the starfish Asterias by Mathews, 1 87, 2, p. 155. PRELIMINARY GENERAL SKETCH 193 both observers independently showing that the polar spindle containsdistinct centrosomes, which, however, degenerate after the formationof the polar bodies, their place being taken by the sperm-centrosome,which divides to
The cell in development and inheritance . rms through the independentand nearly simultaneous researches of myself on the ^^g of Toxo-pneustes, of Mathews on Ajbacia, and of Boveri on Echinus. Nearlyat the same time a careful study was made by Mead (95, 98, i) ofthe annelid ChcBtopterics^ and of the starfish Asterias by Mathews, 1 87, 2, p. 155. PRELIMINARY GENERAL SKETCH 193 both observers independently showing that the polar spindle containsdistinct centrosomes, which, however, degenerate after the formationof the polar bodies, their place being taken by the sperm-centrosome,which divides to form an amphiaster before union of the nuclei, asin Rhynchelmis. Exactly the same result has since been reached byHill (95) and Reinke (95) in SpJiczrecJiinus, by Hill in the tunicatePhalliisia, by Kostanecki and Wierzejski (96) in Physa (Fig. 89),and by Van der Stricht (98) in TJiysaiiozodn; and in all of these thecentrosome is likewise shown to arise from the middle-piece or inits immediate neighbourhood. Among others who have produced. Fig. 98. — Fertilization of tlie egg in tlie copepod, Cyclops streniius. [RlJCKERT.]A. Sperm-nucleus soon after entrance, the sperm-aster dividing. B. The germ-nuclei ap-proaching; (f, the enlarged sperm-nucleus with a large aster at each pole; 9, the egg-nucleusre-formed after formation of the second polar body, shown at the right. C. The apposed reticulargerm-nuclei, now of equal size; the spindle is immediately afterward developed between the twoenormous sperm-asters; polar body at the left. evidence that the cleavage-centrosome stands in definite relation tothe spermatozoon, may be mentioned Oppel (92) in reptiles, Brauer(92) in Bra7icJiipus, Henking (92) in insects, Riickert (95, 2) inCyclops, Sobotta (95) in the mouse and (98) Amphioxus, Ziegler (95)in Diplogastcr and RJiabditis, Castle (96) in Ciona, Korschelt(95) in Ophryotrocha, Meyer (95) in Strongyliis, Griffin (96, 99)in Thalassema, and Coe (98) in Ccrebratulus. Beside the forego
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectcells, bookyear1902
