THE SEXUAL ORGANS. 229 



death (on one occasion Valentin noticed faint motion at the 

 end of even 84 hours), and in the female genital organs in the 

 Mammalia, they exhibit motion even after seven or eight days. 

 Water at first renders the motions more lively, but they soon 

 cease, and the filaments are not unfrequently curved in a loop- 

 like form. Blood, milk, mucus, pus, syrup, and a diluted 

 saline solution usually have no injurious effect ; but it is other- 

 wise with urine and bile, the former particularly, when it is 

 strongly acid or much diluted. All chemical reagents, acids, 

 metallic salts, caustic alkalies, &c, cause the motion to cease, 

 as do narcotics when they act chemically upon the filaments, or 

 are too much diluted. 1 



The formation of the spermatic filaments and of the semen, 

 it is true, usually ceases in old age, although they are not 

 unfrequently found in men of 60, 70, or even 80 years of age, 

 and even accompanied — though this, it must be confessed, is an 

 unusual phenomenon — with the procreative faculty. After 

 diseases, the spermatic filaments are as often found to be pre- 

 sent as absent ; and with respect to the cause of their deficiency 

 only this much can be stated, that it appears to depend prin- 

 cipally upon impaired nutrition. 



§ 199. 



Membranes, vessels, and nerves of the testis. — The testes, 

 together with their fibrous tunic, and a portion of the epididy- 

 mis, are immediately invested by the tunica vaginalis propria 

 (fig. 255 b, d,f), a delicate serous membrane, which, at one 

 time, was a part of the peritoneum, and corresponds with it in 

 structure. Its epithelium, constituted of a layer 0005'" thick, 

 of clear, polygonal cells, 0*005 — 0008'" in size, with distinct 

 nuclei, and occasionally with isolated, yellowish pigment-gra- 

 nules rests, on the testis, immediately upon the fibrous mem- 

 brane, or at all events in this situation, is inseparably united with 

 the fibrous coat constituting the tunica adnata testis, or the 

 visceral lamella of the t. v. propria; whilst on the epididymis the 

 serous coat, may be distinctly separated, and, like its parietal 



1 Chloroform exerts the same influence upon the spermatozoa as it does upon all 

 motile tissues in animals and plants. The spermatozoa of the Frog, when exposed 

 to the dilute vapour of chloroform, gradually cease to move, regaining their motile 

 property upon exposure of the fluid to the air, (at any rate many of them) and the 

 filaments thus revivified, appear to retain all their impregnating power. — [Eds.] 



