GENERATION. 



when from ten to twenty spermatozoids are developed in a 

 single vesicle, the heads and tails are arranged regularly, 

 side by side ; but when but two or three are observed, their 

 arrangement is irregular. The vesicular envelopes finally 

 disappear and the spermatozoids are liberated ; but this 

 only occurs in the rete testis and in the epididymis. In the 

 epididymis and the vasa deferentia, the spermatozoids are 



FIG. 82. 



Development of the spermatozoids in the rabbit. a, a, spermatozoids; &, spermatic cell con- 

 taining fourteen nuclei, two of which contain each a head of a sperm atozoid developed ; c, 

 spermatic cell containing two secondary cells, each one provided with a nucleus from which 

 two spermatozoids are to be developed; d, spermatic cell with one nucleus; e, sper- 

 matic cell containing a secondary cell with a nucleus ; h, bundle of spermatozoids. (LiE- 

 GEOIS, Traite de pkysiologie, Paris, 1869, p. 200.) 



motionless, though they are not enclosed in vesicles, appar- 

 ently from the density of the substance in which they are 

 embedded ; for movements are sometimes presented when 

 the contents of the vasa deferentia are examined with the 

 addition of water or saline solutions. Once in the vesiculse 



