SKCT. I97.] 



Sl'KKMATCZOA. 



431 



o 



of a viscid fluid, and innumerable small, linear corpuscles, named 

 the spermatic animalcules or spermatozoa (spermatozoids), -which 

 arc endowed with peculiar movements. These Fig. iso. 



spermatozoa are perfectly homogcncotis, soft 

 corpuscles, in which we may distinguish a 

 thicker part, the body or head, aud a fili- 

 form appendage, called the thread or tail. 

 The former is flattened, pyriform when 

 viewed from the side, with the pointed- end 

 directed forwards; seen from the surface, it 

 is egg-shaped, or even rounded off anteriorly, 

 whilst at the extreme anterior end, it is 

 slightly hollowed like a cup, so that it ap- 

 pears at one moment clear, at another mo- 

 ment dark in the middle. The body is 

 00016"' to 0-0024'" in length, 0-0008'" to 

 0'ooi5'" in breadth, 0*0005'" to o - o6o8'" in 

 thickness, and, according as it lies upon the 

 surface or upon the edge, its appearance is clearer or darker; it 



Human spermatozoa. 1. 

 magnified 350 times; 2. mag- 

 nified R00 times. n. seen 

 from the side ; b. from the 

 surface. 



Fig. 181. 



f 



always has a peculiar 

 f fatty lustre, and presents 



a dark contour, especially 

 Avhen viewed from the 

 side. The filament is 

 colourless, and measures 

 on an average o'02"' in 

 length. It is flat and 

 tapering ; its greatest 

 width is 0-0003'" to 

 o , ooo5'" at the end near- 

 est the body, the union 

 with which is effected 

 by a constricted neck. 



Development of the spermatic filaments of the bull. a. The free extremity rUIlS 



sperm-cyst, and b, sperm-cells, containing nuclei, which , • , n 



exhil.it a darker anterior and a clearer posterior part ; c, d. OUt into a Very tine point, 



the nuclei developing into spermatozoa; c. further stages ; -1 • M 1 l 



/.a filament almost complete, but still showing a little of the Scarcely Visible even by 



posteriox clear zone in its body ; also two perfect spermato- .1  , . r . 



zoa fr^thc epididymis, one seen from .the surface, the "1G best magnifying pOW- 



other edgewise; >/. sperm-cells becoming pyriform, and T 



about to liberate the contained spermatozoa. Magnified 450 ei'S. In VlgOrOUS mdl, 



the semen in the whole 

 course of the spermatic duct, and in the tail of the epididymis, is 

 composed of these corpuscles, and occasionally of separate granules, 

 nuclei and cells, which would appear to be here accidentally inter- 



