i9"] SHARP— SPERMATOGENESIS IN EQUISETUM 93 



togenous cell. In the second paper (4) the blepharoplast of 

 Equisetum is first described as a crescent-shaped body lying against 

 the nucleus of the spermatid. This body stretches out to form the 

 cilia-bearing thread. The third contribution (5) is a short account 

 of the metamorphosis of the spermatid in Char a, ferns, and Equi- 

 setum. In all of these forms a small body elongates to form a 

 thread upon which small Hdcker arise and grow out into cilia. 

 In a comparison with animal spermatogenesis, Belajeff here 

 homologizes the Korperchen (blepharoplast) in the spermatid, 

 the thread to which it elongates, and the cilia of the plant, with the 

 centrosome, middle piece, and tail (perhaps only the axial filament), 

 respectively, of the animal. The following year, in connection 

 with a further discussion, he figured the details as made out by him 

 in Gymno gramme and Equisetum (6). In Gymnogramme the 

 blepharoplasts appear at opposite sides of the nucleus in the 

 spermatid mother cell, while in Equisetum a single blepharoplast is 

 first figured lying close to the nucleus of the spermatid, behaving 

 as outlined in the earlier accounts. 



One of the most interesting cases is that of Marsilia, first 

 described by Shaw (76). According to this investigator a small 

 granule or " blepharoplastoid " appears near each daughter nucleus 

 of the mitosis which differentiates the grandmother cell of the 

 spermatid. During the next division these divide but soon dis- 

 appear, and a blepharoplast appears near each spindle pole. In 

 the next cell generation (spermatid mother cell) the blepharoplast 

 divides to two which become situated at the spindle poles in the 

 final mitosis. In the spermatid the blepharoplast shows a small 

 internal granule; this multiplies to several and forms a band which 

 elongates spirally with the nucleus and bears the cilia. Shaw sees 

 in these facts no ground for the homology of the blepharoplast and 

 the centrosome. Belajeff's paper dealing with Marsilia appeared 

 in the following year (7). He found that centrosomes occur at the 

 poles during all, excepting possibly the first, of the series of divisions 

 which result finally in the 16 spermatids. After each mitosis the 

 centrosome divides to two which occupy the poles during the 

 next mitosis, and in the spermatid it performs the function of a 

 blepharoplast. Belajeff regards this as a strong confirmation 



