130 



ARCHEGONIATES. 



cytoplasm along whose outer edge is a delicate thread or band derived 

 also from the cytoplasm, and from which the cilia are developed (Fig. 

 52, A). Belajeff was the first to call attention to the cilia-bearing 

 band, which he observed in the development of the spermatozoid in a 

 fern and in Equisetum, He also reported a similar body in Chara, 

 In speaking of the body which gives rise to the cilia-bearing band, 

 Belajeff used the term "Nebenkern," because of its apparent resem- 

 blance to a body of that nature in the spermatid of certain animals. 

 In 1897 Webber described the development of the cilia-bearer in the 

 spermatozoid mother-cell of Zamia, and gave to it the name bleph- 



D 



E 



G 



H 



FIG. 51. Development of sperma- 

 tozoid in Gymnogramme sul- 

 fhurea.(A.her Belajeff.) 



A, grandmother-cell of spermatozoid with two primordia of bleph- 



aroplasts. 



B, two spermatozoid mother-cells, each with its blepharoplast 



primordium. 



C, spermatozoid mother-cell rounded off. 



D, the young blepharoplast has begun to elongate. 



E, stage a little older than D. 



F, blepharoplast much elongated; its anterior end extends out to 



plasma membrane. 



G, transformation of nucleus has begun ; it is somewhat pear- 

 shaped, being concave on side turned from blepharoplast: end 

 which will be anterior in mature sperm is pointed. 



H, later stage; cilia have been developed from the blepharoplast. 



aroplast. 1 Ikeno and Hirase, who were the first to discover the 

 spermatozoid in certain gymnosperms, described the development of 

 the cilia-bearing band in the spermatozoid of Cycas and Ginkgo. 



Belajeff and the two Japanese investigators consider the body 

 developing into the blepharoplast as a centrosome. The author is 

 convinced that it has been clearly proved that the blepharoplast is not 

 a centrosome, nor, as yet, has any phylogenetic relationship been 

 shown to exist between the blepharoplast and the centrosome as we 

 know this structure in plants. 2 



THE SPERMATOZOID. 



The development of the spermatozoid in Onoclea, as described by 

 Shaw ('98), is quite similar to that of Gymnogramme according to 



1 From j3Ac<f>apij, eyelash or cilium ; and irAacrros, formed. 



2 See Introduction, p. 46. 



