290 Trans. Acad. Sci. of St. Louis. 



as cytoplasm. At the end of this cytoplasmic portion an 

 enlargement may sometimes be demonstrated (tig. 4) at or 

 near which the cilia seem to be attached. I have not been 

 able to stain them to show their actual points of attachment. 

 At the time of fertilization I have not been able to distinguish 

 any cytoplasmic vesicle attached to the blunt end of the 

 nucleus, although Belajeff describes it as present. Shaw 

 describes it as actually torn from the moving spermatozoid 

 as it becomes entangled in the slime at the mouth of 

 the archegonium. I have observed it in the free swim- 

 ming spermatozoid. The nuclear portion is enveloped by 

 a cytoplasmic covering (Hiille of Belajeff) which appears 

 to be continuous with the forward coils which bear the 

 cilia. This envelope or covering has been variously described. 

 Guignard claimed that the entire body of the spermatozoid 

 except the cilia and the vesicle behind was nuclear. Of this 

 the forward coil bearing the cilia showed no chromatin though 

 it was continuous with the chromatiu-bearing portion. Bela- 

 jeff finds the anterier end a cytoplasmic band inclosing a 

 deeply staining fiber or thread derived from the " Neben- 

 kern," curving around the nuclear portion and, presumably, 

 inclosed in the same cytoplasmic covering (Hiille) as the 

 nucleus. Schottliinder described in addition to the same 

 cytoplasmic envelope a band or " Segel " the whole length of 

 the nuclear portion. I have seen a similar appearance at 

 times, but on the basis of my observations of the living sper- 

 matozoid and the fate of its several parts in the fertilization 

 process, I am convinced that the cytoplasmic envelope does 

 not fit the nucleus closely. The nucleus lies in one side, so 

 that the appearance of a band may be due to the collapse or 

 partial collapse of the portion not distended by the nucleus. 

 This explanation would correspond more nearly with the 

 observation of Shaw for Marsilia where he finds a thread 

 derived from the *♦ blepharoplast " not only in the forward 

 coils but traversing the full length of the nuclear portion and 

 even extending out behind it. It also agrees with the state- 

 ment of Belajeff that the thread derived from the *' Neben- 

 kern " lies in one edge of the cytoplasmic band which consti- 

 tutes the forward end, while the pointed end of the nucleus 



