326 



GENERATION. 



puscles or granules with which they come in contact. This 

 is supposed to be an indication of the vitality of the sperma- 

 tozoids, which are not thought to be capable of fecundating 

 the ovum after their movements have ceased. Under favor- 

 able conditions, particularly in the generative passages of the 

 female, the movements continue for days ; and this fact is 

 important, as we shall see hereafter, in its bearing upon 

 the limits of the time of fecundation. 



Microscopical examination does not reveal any very dis- 

 tinct structure in the substance of the spermatozoids. The 



head is about Winr of 



_ o u o o 



an inch long, ^^ of an 

 inch broad, and - a g 1 

 of an inch in thickness. 

 The tail is about -g-J-^ of 

 an inch in length. La 

 Yalette St. George has 

 found, in man and many 

 of the inferior animals, 

 the " intermediate seg- 

 ment " described first 

 by Schweigger - Seidel, 1 

 though he does not agree 

 with Schweigger-Seidel 

 that this portion is mo- 

 tionless. 3 The length of 

 the intermediate seg- 

 ment is about TO Vo- of an mcn - It; is usua % described as 

 the beginning of the tail ; and the only difference between 

 this and other portions is that it is a little thicker. 



According to Kolliker, water speedily arrests the move- 

 ments of the spermatozoids, which may be restored by the ad- 



1 SCHWEIGGER-SEIDEL, Veber die Samenkorperchen und ihre Entwiclclung. 

 Archivfur mikroskopische Anatomic, Bonn, 1865, Bd. i., S. 319. 



2 LA VALETTE ST. GEORGE, in STRICKER, Manual of Human and Comparative 

 Histology, The New Sydenham Society, London, 1872, vol. ii., p. 161. 



Human spermatozoids. Mafmiflod 800 diameters. 

 (LtrscHKA, Anatomie ctes Menschen, Tubin- 

 gen, 1864, Bd. ii., S. 272.) 



