STRUCTURE OF THE SPERMATOZOA. 



149 



In the Dog the head is pyriform : in the Cat, oval ; the tail 

 arising from the broader side. 



The head of the spermatozoa in the Hedgehog appears trun- 

 cated below, with lateral insertion of the tail. 



The spermatozoa of the Bat also present the form of a trun- 

 cated oval, and the tail is attached to the middle of its lower 

 border. 



In the Monkey the head is oval, with the broader extre- 

 mity towards the tail. 



The spermatozoa of Man present an oval head, with a 

 thickened and rounded posterior border, to which the tail is 

 attached. The head is prolonged anteriorly into a thin disk, 



Fig. 181. 



Fig. 181. Spermatozoa of Man. a, undeveloped ; 6, mature. 



depressed in the centre. Hence when seen laterally, 

 le head appears more or less pyriform. The thickening is some- 

 diat greater on one side than upon the other, as was pointed 

 it to me by Leuckart. The length of the head amounts to 

 the breadth, 3 n ; the greatest thickness, 1 p. The tail is 

 bher attenuated where it is attached to the head, enlarges 

 1 n, and then runs out to a point for a length of 50 /*. 



STRUCTURE OF THE SPERMATOZOA. Much interesting in- 

 formation has recently been obtained in regard to the structure 

 of the spermatozoa. 



According to Valentin,* the spermatozoa of the Bear present 



* Zeitschrift fiir rationelk Medicin, 3 R., Band xviii., p. 217; and 

 Band xxi., p. 39. 



