Xn EQUISETINEAl 449 



Development of the Spermatozoids 



The large size of the spermatozoids of Eqitisctum makes 

 them especially suitable for the study of their development, and 

 this was traced with some care in E. telmateia. Belajeff (6), 

 more recently, has studied the development of the si)ermatozoid 

 in E. arvense. 



The nuclei of the sperm cells previous to their final division 

 are globular and show one, sometimes two, small but distinct 

 nucleoli, and numerous chromosomes. In exceptional cases the 

 two blepharoplasts could also be seen. Previous to the final 

 division the latter take their place on opposite sides of the now 

 somewhat flattened nucleus, whose nucleolus cannot be distin- 

 guished and whose chromosomes are very distinct, short, curved 

 bodies. Their number could not with certainty be determined. 

 The nucleus passes through the various karyokinetic phases, 

 and the blepharoplasts occupy the poles of the nuclear spindle. 

 The resting nuclei, as in other cases, show no nucleolus. Fig. 

 261, F, shows the earliest stage in the differentiation of the 

 spermatozoid, and this corresponds exactly with what I have 

 observed in various Ferns, and differs somewhat from Buch- 

 tien's figures of corresponding stages. The nucleus, which is 

 not noticeably lateral in position, shows a narrow cleft upon one 

 side. Seen in profile (Fig. 261, F, i), one side projects some- 

 what more than the other, and becomes the anterior end, which 

 later becomes thinner than the posterior part. I was unable to 

 see that this forward part behaved differently from the hinder 

 part with regard to the nuclear stain employed, nor could I sat- 

 isfy myself of the presence of the cytoplasmic anterior prom- 

 ,inence which Strasburger ((n), IV., PI. m) figures in the 

 Ferns. 



In some cases the blepharoplast could be seen (Fig. 261, E- 

 H) and in the older stages this was much elongated, extending 

 beyond the pointed end of the nucleus ; but perhaps owing to 

 the fixing agent used — chromic acid — the formation of the cilia 

 from the blepharoplast did not show at all clearly, while Belajeff 

 indicates (Fig. 261, I) that they are very conspicuous. Per- 

 haps also due to unsatisfactory staining, my preparations did 

 not show at all clearly the cytoplasmic envelope about the nu- 

 cleus which is so conspicuous in Belajeff's figures. (See Fig. 

 261, J.) 



The body rapidly elongates and becomes quite homogeneous, 

 29 



