94 



INTRODUCTION TO CYTOLOGY 



ment of two of the black granules. Very conspicuous radiations develop 

 about them, and after mitosis they form ribbon-like cilia-bearing bands 

 in the spermatids as in the other cycads. 





CVAtO.CUWU.id 



FIG. 34. Spermatogenesis in Dioon edule. 



A, "body cell," with black granules in cytoplasm. X 1890. B, two blepharoplast* 

 differentiated. X 1890. C, body cell with two blepharoplasts; prothallial and stalk cells 

 below. X 237. D, fragmentation of blepharoplast in spermatid as spiral band begins to 

 form. X 1890. E, portion of edge of spermatozoid, showing spiral band cut at two points 

 and cilia growing from it. X 945. (After Chamberlain, 1909.) 



Ikeno in 1898 expressed the opinion that the blepharoplast of Ginkgo 

 and the cycads is a true centrosome, a view shared by Chamberlain (1898) 

 and Guignard (1898). Two additional papers dealing with this subject 

 were published by Ikeno (1904, 1906). In the first of these he made 

 comparisons with analogous phenomena in animals which he believed to 



