94 



INTRODUCTION TO CYTOLOGY 



tnent 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. 



*-;,'- 



. .-' ". v ^fepSi*stt^ 



*-' "'?'' 'i : ''^%^%$$3&& 



FIG. 34. Spermatogenesis in Dioon edule. 



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

 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 A he made 

 comparisons with analogous phenomena in animals which he believed to 



