GYMNOSPERMS. 



'47 



primordia of the blepharoplasts (Fig. 58, B) . This is true for Zamia, 

 according to Webber, and for Ginkgo, according to Hirase. At this 

 stage each primordium of the blepharoplast is transformed into a group 

 of fine rods about which the radiations, although not so pronounced, 

 are still present (Fig. 58, C). When, however, the daughter chromo- 

 somes have arrived at the poles of the spindle, each blepharoplast has 

 become a mass, or an accumulation, of granules, and the radiations 

 can scarcely be recognized. 



At the close of nuclear division each daughter-nucleus is homo- 

 geneous, presenting a small number of nucleoli. A cell-plate is formed 

 and the division of the generative cell completed (Fig. 58, D). The 

 next step is characterized by the behavior of the mass of granules of 

 the young blepharoplast. These are arranged close to the nucleus 

 into a more or less short and broad band whose granular nature is still 

 evident. Seen in profile a number of radiations appear extending out 

 from the band toward the periphery of the cell (Fig. 59, A). These 

 radiations are the developing cilia of the spermatozoid. Whether the 

 cilia are transformed radiations, or arise anew, is a question. Ikeno 

 ('98, p. 1 80) is inclined to think that the former mode of origin is the 

 more probable. 



In the meanwhile the nucleus develops a beak which becomes con- 

 nected with the ciliated band (Fig. 59, A). The development of the 

 nuclear beak and the arrangement of the granules into a band take 

 place simultaneously, so that it is not known which phenomenon is of 

 first importance. If the formation of the beak took the initiative, then 

 it would be reasonable to suppose that the direct cooperation of the 

 nucleus in the development of the band is indispensable. In Zamia, 

 according to Webber, no such nuclear beak occurs in the development 

 of the spermatozoid. Subsequent to this stage in the development of 

 the band its granular nature is no longer recognizable ; it appears as a 

 thin homogeneous thread (Fig. 59, B). The further behavior of the 

 blepharoplast seems to be characteristic of spermatogenesis in Cycas, 

 Zamia, and Ginkgo. The ciliated band extends itself in a spiral 

 which ultimately makes five turns around the hemispherical cell, 

 always remaining near its surface just beneath the plasma membrane. 

 During this process the nucleus increases in size and becomes some- 

 what pear-shaped. Its beak, to which is attached apparently one end 

 of the band, increases in length until it almost reaches the surface of 

 the cell (Fig. 58, E, and Fig. 59, B). The free end of the band con- 

 tinues its spiral course around the cell a short distance beneath the 

 plasma membrane. The direction of the spiral is parallel with the 



