PTERIDOPHYTA. 



'33 



in some cases in which the stain was well washed out the structure 

 appeared coarsely reticulate or granular. This was observed in sper- 

 matozoids of Onoclea struthiopteris that were killed on the slide in 

 chrom-osmic-acetic acid and stained in safranin gentian-violet and 

 orange G. 



The posterior turns of the spermatozoid embrace the vesicle, which 

 presents a very fine reticulum, and in which coarse granules are held, 

 among them being small starch grains. The author has observed that 

 the vesicle of Onoclea struthiopteris became separated from the 

 spermatozoids a short time after their escape from the antheridium ; 

 for, of the many hundreds fixed and stained upon the slide a few 

 minutes after their escape from the antheridia, relatively few were 

 found with the vesicle adhering. 



The development of the spermatozoid of Marsilia, according to 

 Shaw ('98) and Belajeff ('99), differs in certain important details 

 from that of Onoclea. As this process is known in so few of the 

 Pteridophyta, it is perhaps well to present briefly the facts as they 

 ai-e known in one of the heterosporous forms. 



At the close of the second from the last division in the spermogenous 

 tissue of Marsilia vestita, or that leading to the great-grandmother- 

 cell of the spermatozoid (the primary spermatocyte of Shaw), there 

 appears at each pole of the spindle, or near it close to the daughter- 

 nucleus, a small body which is called by Shaw a blepharoplastoid. 

 During the resting stage of the nucleus the blepharoplastoid seems to 

 divide. The two halves increase in size and remain together near the 

 nucleus. As soon as the nucleus of the great-grandmother-cell begins 

 to divide, the pair of blepharoplastoids move away from the nucleus 

 and remain at a position in the cytoplasm between one pole of the 

 spindle and the equatorial plane, until the metaphase, or early anaphase, 

 when they disappear. About the same time, or a little later, a small 

 blepharoplast appears near each pole of the spindle. At the close of 

 the division the blepharoplast lies near the nucleus of the grand- 

 mother-cell of the spermatozoid (secondary spermatocyte or sperma- 

 tocyte mother-cell of Shaw). It now divides, and the two daughter 

 blepharoplasts increase in size and separate from each other, at the 

 same time moving away from the nucleus (Fig. 53, A, B). Each 

 takes a position near the pole of the future spindle but always a little 

 to one side of its longitudinal axis. They increase in size and remain 

 apparently unchanged in structure until the anaphase, when each seems 

 to be hollow (Fig. 53, B, C). 



As soon as the nucleus of the spermatozoid mother-cell (spermatid) 



