94 



INTRODUCTION TO CYTOLOGY 



menl oi two oi 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. 



rif)r\ ■ ... -\ 



A 



B 











Ctarlei J . Otaml* rUn del. 





*•-* 





Fig. 34. — Spermatogenesis in Dioon edule. 



diff^&fed ° e x 18q(» h b r° } k f a ^! eS £ 7*°^™' X 189 °- * two blepharoplasts 



below V 2 qV n f + + y Ce V^ u tW ° ble P har «P^sts; prothallial and stalk cells 



' X 1890 F T^r ° blepharoplast in spermatid as spiral band begins to 



m. X 1890. £, portion of edge of spermatozoid, showing spiral band out at two noints 



and cdia growing from it. X 945. {After Chamberlain. 1909.) P 



Ikeno in 1898 expressed the opinion that the blepharoplast of Ginkgo 

 a ad 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 firsr of these he made 

 comparisons with analogous phenomena in animals which he believed to 



