DEVELOPMENT OF THE SPERMATOZOA. 



161 



exhibited a kind of nodule at its anterior extremity. The 

 tail sprouted from the opposite side of the cell, and soon 

 )rmed a connection with the nucleus. The head continued 

 increase in length, and appeared to be curved, though 



ill always invested by the cell. It then began to assume 



spiral or corkscrew-like form. Ultimately it straightened 

 itself out again, and exhibited a regularly shaped spiral, 

 34 JJL in length, to which was appended a straight tail 85 p 

 in length. 



We thus see there is complete agreement amongst all the 

 Vertebrata in the development of their spermatozoa. 



As regards the Invertebrata, my investigations are not ex- 

 laustive, but this much is certain, that in the Mollusks and 

 Arthropods the tail in part proceeds from a lustrous body 

 lying near the nucleus. Whether this body is a product of the 

 ission of the nucleus or not, is doubtful. I have sometimes 



in it double, and have also seen several nuclei lie near it, as 

 r ell as only a granular mass from which it appeared to have 



Fig. 190. 



Fig. 190. Development of the spermatozoa of Helix nemoralis. 



roceeded. The upper part of each tail invariably appears 

 ickened at its origin, even when it is impossible to distinguish 

 y peculiar body at this point in the ripe spermatozoon. 

 The protoplasm of the cell appears to be here also indispen- 

 ble for the protrusion of the tail. 



VOL. II. M 



