GROWTH OF EGGS AND EGG-STRINGS IN NEPHELIS. 195 



refractive granules, on which account their nuclei are not 

 to be easily seen in a fresh condition. Exposed to fumes 

 of osmic acid and coloured with picro-carniine their nuclei 

 can be clearly made out. Nuclei thus demonstrated gave 

 an average diameter of "005 mm. No nucleolus could be 

 discovered in the nucleus, nor could any cell-membrane 

 be recognised. What significance these free cells possess 

 must be left undecided for the present, but with regard to 

 their origin 1 may make a suggestion. Pressing either an 

 egg-string or the germogen under the cover-glass, a crowd 

 of nuclei and also cells escape together Avith granular pro- 

 toplasm. Some at least of the cells thus set free have 

 exactly the appearance of those found in the ovarian fluid. 

 This fact seems to favour the supposition that these free cells 

 are originally egg-cells, which have become free by the 

 breaking up of egg-strings or of the germogen. Leydig has 

 remarked that these cells probably arise from the epithelium 

 of the ovary-wall. If the above supposition be true his 

 remark is correct in so far that the free cells can be indi- 

 rectly traced to the epithelium. Notwithstanding my special 

 search, I have not met with any case in which these free 

 cells could be traced directly to the epithelial lining of the 

 ovary. 



Together with free cells are sometimes found apparently 

 free nuclei, which stain deeply in picro-carmine. These per- 

 haps have the same origin as the free cells. 



Highly refractive, yellowish granules of the same appear- 

 ance as yolk-granules, are also abundant in the ovarian 

 fluid. 



Several massive aggregations of spermatozoa (spermato- 

 phores ?), each containing an enormous number of sperma- 

 tozoa, are always found in each ovary about the time the 

 laying season begins. It seems probable that the number 

 greatly exceeds that of the spermatozoa which actually 

 penetrate the eggs, and that the superfluous ones dissolve 

 sooner or later, and thus contribute something towards the 

 formation of the ovarian fluid. 



II. Copulation, Abnormal Copulation, 8fc. 



Copulation. — Although it still remains doubtful whether 

 copulation ever occurs in Clepsine, this act has been ob- 

 served in many other members of the leech-family, and 

 described by various authors. 



In the case of the IMediciiial Leech, some authors (No, 6 



