480 



SEMEN. 



more so as the characteristic spiral twistings 

 have not yet assumed that distinctness and 



Fig. 334. 



Cells of Developement with Spermatozoa of the House 

 Sparrow. 



regularity, which they subsequently attain. 

 The presence of the spermatozoa can only be 

 proved with certainty, when they have become 

 free, after the dissolution of their formative 

 cells, the mother cyst still continuing to en- 

 circle them. Thus we may also explain the 

 former conjecture of one of us, R. Wagner, 

 who thought that the spermatozoa of the 

 singing birds had their origin immediately in 

 the interior of the large cysts. 



The spermatozoa of the singing birds do not 

 however lie together irregularly in the inte- 

 rior of these cysts, as in the cock, the pigeon, 

 &c.,but are associated in very definite fascicles, 

 as already described. We are ignorant as to 

 the cause of this arrangement. The number 

 and grouping of the cells of developement in 

 the interior of the cysts do not present any 

 remarkable differences from those in the cock, 

 &c., although the spermatozoa of the latter 

 are constantly devoid of such a regular 

 arrangement. The spermatozoa of the sing- 

 ing birds likewise remain enclosed for some 

 time by the membrane of the mother cysts. 

 At the commencement they lie with re- 

 verted tails close to the interior wall of 

 the cysts, which then assumes an oval form 

 (fig. 335.)- Subsequently the tail ends of 



Fig. 335. 



Mother Cell with a Bundle of Spermatozoa from 

 Fringilla domestica. 



the spermatozoa remove themselves further 

 and further from the anterior bodies. The cyst 

 bursts where the points of the tails are 

 situated, and the bundles, which are still 

 covered at the anterior end by the remains 

 of the cyst, as if by a cap, then assume 

 the shape of a retort, or of a knee-shaped 

 bent cylinder. Even in cases in which the 

 spermatozoa have perfectly separated them- 

 selves (fig. 336.), this remainder of the for- 

 mer cyst can generally be traced. We may 

 also see very distinctly a tough albuminous 

 substance between the individual sper- 

 matozoa, from which the tail ends project 

 freely. 



These proportions experience a small mo- 

 dification in those singing birds, in which the 



Fig. 336. 



A Bundle of Spermatozoa from Fringilla ccelebs. 



tails of the spermatozoa are shorter than 

 among the Lanidae. The cysts here retain 

 almost entirely their original form, or do 

 not enlarge to any extent (fig. 337.). The 



Fig. 337. 



Bundle of Spermatozoa in the interior of a Cyst of 

 Lanius. 



spermatozoa in this case lie quite straight in 

 the cyst from the commencement, and sub- 

 sequently pierce the posterior end of it with 

 their tails. 



REPTILIA. The spermatozoa of the rep- 

 tilia possess the same shape as those of birds ; 

 that is to say, an oblong cylindrical body, and 

 a very fine hair-like tail. 



No great differences present themselves in 

 the form of these elements among the rep- 



