1909] CHAMBERLAIN— SPERMATOGENESIS IN DIOON 223 



THE BLEPHAROPLAST 



The origin of the blepharoplast is not easy to determine. In 

 Zamia, Cycas, and Ginkgo, the blepharoplast, when first recognizable, 

 is a small sharply staining granule in the cytoplasm of the body cell. 

 We must admit that the same is true of Dioon, but a study of the black 

 granules led us to surmise that blepharoplasts, in their origin, are 

 simply these granules derived from the nucleus. It would follow- 

 that not two but several blepharoplasts might begin to develop. Why 

 only two should become differentiated is not clear. The blepharo- 

 plast, in all the early stages of its development, takes an intense homo- 

 geneous black color with iron alum hematoxylin, never behaving like 

 the gray bodies. Sometimes the cytoplasm about one or more black 

 granules becomes dense and homogeneous, quite unlike the usual 

 alveolar structure, and resembling the archoplasm which surrounds 

 young centrosomes (fig. i 3 ) . It is possible that blepharoplasts may 

 begin their growth in this way. 



After enlarging considerably, two blepharoplasts become unmis- 

 takable through their influence upon the surrounding cytoplasm, 

 *'hich takes on a radiate arrangement with the blepharoplast as a 

 center (fi gSm j 5j I( ^ m At first? the relations are nothing more than 

 the intersections of alveoli (fig. 16), but as the walls of the alveoli 

 become less distinct, the radiations become definite granular filaments, 

 extending from the blepharoplast to the periphery of the cell. Many 

 Ae filaments are simple, but branching is very common (figs. 17, 22) . 

 , The appearance of the filaments in preparations indicates a stream- 

 ing movement, especially toward the blepharoplast. That the 

 radiations seen in sections are streams of cytoplasm is indicated by 



e fact that exactly similar structures are found in the pollen tube, 

 * ere there is certainly a strong streaming movement. An almost 

 ^tive proof that the filaments are streams of cytoplasm is furnished 



) r artifacts. I n cutting out the top of the female gametophyte with 

 of S * rche g°nia, the least pressure will cause some of the cytoplasm 

 Th> e eggs to be squeezed out through the necks of the archegonia. 

 arch eSCaping Ooplasm, streaming out through the neck of the 

 Z ] eg0mum ' shows very numerous filaments with a structure iden- 

 ofV Vlth - that ° f the radiati °ns about the blepharoplast, and in case 

 e artlfact there is no doubt that the filaments are nothing but 



