ARCHOPLASM, CENTROSOME, AND CHROMATIN 

 IN THE SEA-URCHIN EGG. 



EDMUND B. WILSON. 



In a short paper published in January, 1895,^ I showed that 

 the fertilization of the egg in the sea-urchin Toxopiieiistes 

 variegaUts Kg. differs radically from Fol's account of the 

 "Quadrille of Centers" in Strongylocentrottis lividus, and at 

 the same time A. P. Mathews announced results nearly iden- 

 tical with mine in the case of the ?,Q?i-urch\n Aj'bacia piuictulata, 

 and the star-fish Asterias Forbesii. Since the appearance of 

 that paper Boveri has published the results of an independent 

 investigation of the fertilization of Echinus inicyotiibeixiilatiis^ 

 which, as far as the essential phenomena of fertilization are 

 concerned, agree "fast Punkt fiir Punkt" with those of Mathews 

 and myself, — a confirmation which seems to render the evi- 

 dence against the " quadrille " nearly conclusive as far as the 

 echinoderms are concerned. 



On two points only is there an apparent conflict between 

 Boveri's results and my own. One of these, as Boveri himself 

 points out, is merely a difference of interpretation, or rather of 

 terminology, since the large reticulated spherical body forming 

 the central mass of the asters of the karyokinetic figure (" as- 

 trosph^re" of Fol, '' centrosphere'' of Strasburger) is called a 

 centrosome by Boveri, whereas I termed it the " attraction- 

 sphere " or "archoplasm-sphere," and asserted the absence of 

 a "differentiated centrosome" (/. c, p. 326). 



The second point appears at first sight to be a difference of 

 fact, since Boveri describes the sperm-aster as containing from 

 the first a minute deeply staining centrosome of the usual type, 

 whose division into two precedes the fission of the sperm-aster. 



1 Journal of Morphology, X, i, p. 319. 



2 Ueber das Verhalten der Centrosomen bei der Befruchtung des Seeigel-Eies, 

 nebst allgemeinen Bemerkungen iiber Centrosomen und Verwandtes. Verh. der 

 Phys.-Med. Ges. Wurzburg, N.F., XXIX, i, 1895. 



