582 THE AMERICAN NATURALIST. [VOL. XXXVI I L 



definite granules in the band as it develops from the compact 

 spherical blepharoplast. 



There appeared almost simultaneously with the foregoing con- 

 tribution of Belajeff a paper by Shaw ('QBb) on Onoclea and 

 Marsilia. Shaw investigated the cell divisions preceding the 

 formation of the spermatids in Marsilia and discovered some 

 very interesting conditions. The two blepharoplasts which are 

 found in the mother cell of the spermatid are foreshadowed by 

 smaller bodies which appear at the poles of the spindle in the 

 two previous mitoses. The first of these structures was called 

 a blepharoplastoid. The blepharoplastoid first appears besides 

 the daughter nucleus after the third mitosis previous to the dif- 

 ferentiation of the spermatids. There is therefore one for each 

 nucleus of the grandmother cell of the spermatid. This bleph- 

 aroplastoid divides but the halves remain close together and 

 the pair passes to one side of the cell. With the next mitosis 

 (the second previous to the differentiation of the spermatids) 

 two new structures are formed at the poles of the spindle and 

 from these the blepharoplasts arise. They accompany each 

 daughter nucleus after this mitosis into the mother-cell of the 

 spermatid. Then each divides and the two blepharoplasts pass 

 to opposite sides of the nucleus which prepares for the final 

 mitosis of the series. This division gives a daughter nucleus to 

 each blepharoplast and the spermatid is thus organized. The 

 later history of the spermatid as it changes into the sperm is 

 identical with Belajeff 's results. 



Belajeff ('99) followed Shaw's account of Marsilia with a study 

 of the same form and came to very different conclusions which 

 have to do chiefly with his belief that the blepharoplast is a cen- 

 trosome, a view that will presently be considered in connection 

 with the opinions of Strasburger and others. Belajeff found 

 centrosome like bodies (blepharoplastoids of Shaw) at the poles 

 of spindles in various mitoses preceding the formation of the 

 spermatids with their unquestioned blepharoplasts. He is not 

 willing to concede that these centrosome like structures pass 

 into the cytoplasm to disappear there as Shaw states for the 

 blepharoplastoids. He also found the blepharoplasts at the poles 

 of the spindles, which was not observed by Shaw, and holds that 

 they have a part in spindle formation. 



