476 



SEMEN. 



margin of the body which projects at the 

 posterior part into an obtuse angle. In the 

 rat (fig- 325. A) the body is very long, 

 but narrow in proportion, and bent like 



Fig. 325. 



A. Spermatozoa of the Eat; B, of the common Mouse. 



a sabre at the anterior extremity. The 

 body of the spermatozoa of the domestic 

 mouse is shorter, and may be compared 

 to a bent bistoury. The anterior end, how- 

 ever, is likewise drawn out into a short point, 

 which in the field mouse is very slightly de- 

 veloped. The differences in the caudal appen- 

 dages of the spermatozoa among the mammalia 

 may be reduced to mere differences in length 

 and thickness. In all of them the anterior part 

 attached to the body distinguishes itself from 

 the posterior part by its thickness, but 

 not always to the same extent. Wherever 

 the spermatozoa distinguish themselves by 

 their length, the tail is likewise proportionably 

 thick. 



Dujardin* occasionally observed in the 

 spermatozoa of men, at the commencement 

 of the tail part, a small irregularly shaped 

 protuberance, which Kolliker (who had like- 

 wise observed this in the semen of rabbits) 



* Annal. des Sciences, 1837, t. vii. p. 291. 



supposes to be a mere temporary pheno- 

 menon only a phenomenon of developement 

 and that it subsequently disappears, whilst 

 its adhesive matter is expended in the pro- 

 longation of the tail. This assumption like- 

 wise appears to us possible, although it is 

 remarkable that such swellings or protuber- 

 ances are so rarely met with, and, therefore, 

 certainly cannot be considered as constant 

 associates of the developement. We have only 

 observed a few cases of this description, and 

 that principally in the semen of rabbits. The 

 swellings, which in their physical condition, 

 especially in their refracting power, coincide 

 entirely with the anterior body, have gene- 

 rally a globular shape, but exhibit otherwise 

 many differences in size and position. They 

 are found sometimes at the commencement 

 of the tail part, sometimes rather remote from 

 it. It appeared to us as if the respective ap- 

 pendages were formed less by a swelling of 

 the tail fibre, than by a peculiar enclosing 

 matter. It seemed to us, at least in a single 

 spermatozoon, as if the tail could be clearly 

 distinguished in the interior like a peculiar 

 fibre. Further investigations on this subject 

 are still necessary. 



The spermatozoa of the mammalia generally 

 lie very irregularly and confusedly. At times, 

 however, they are grouped together (as we 

 have especially found in the rat, the guinea 

 pig, and rabbit, and as others have likewise 

 observed in men) in very regular fascicles or 

 bundles, which are formed by the bodies of the 

 spermatozoa adhering by their lateral surfaces, 

 as may be often observed with the blood glo- 

 bules.* It is uncertain, however, whether 

 this group-like association of the spermatozoa 

 is dependent, like that of the blood globules, 

 on definite physical processes. 



The developement of the spermatozoa takes 

 place among the mammalia in the interior 

 of vesicle-shaped globules, which fill up the 

 separate little canals of the testicles in great 

 quantity. Kolliker has traced this mode of 

 developement first of all in the guinea pig 

 (which is very convenient for these in- 

 vestigations) ; likewise in the domestic mouse ; 

 but has subsequently, after more extensive 

 researches, determined that the mode of de- 

 velopement in all the mammalia is the same. 

 These developing vesicles have pretty uni- 

 formly a size of about ^fo'", but intermixed 

 with them there are frequently found vesicles of 

 a smaller and of a larger diameter (to T*h/")' 

 Taken from a fresh dead body, and when ex- 

 amined without being treated with water or 

 any other agent, they are as clear as glass, 

 possessing a delicate contour, and perfectly 

 homogeneous contents. The latter, however, 

 coagulates very readily, assuming thereby a 

 granular quality ; but this we cannot con- 

 sider as its natural condition. 



Most of these vesicles are free within the 

 little seminal canals (fig. 326. A, B, c). They are 

 frequently surrounded by a cellular enclosure, 



* Vide Wagner, Icones Physiolog. 

 Elements of Physiology, p. 10. fig. 4. 



tab. 1. fig. 2. 



