ORGANS OF THE BODY. 561 



is 0-0061, and the terminal filament 0'0406. Both the head and middle 

 portion appear rigid, leaving the end fibre alone movable. That a differ- 

 ence exists between envelope and contents in the sper- 

 matozoa, as maintained by Grohe and Schweigger-Seidel, C3 a 

 we do not think has been yet clearly proved. 



Throughout the whole animal kingdom semen is pos- 

 sessed of certain definite form -elements. But though 

 the prevailing shape of these spermatozoa is filiform in all 

 animals, nevertheless they present extremely interesting 

 and considerable varieties of appearance, reminding us of 

 the similar though much less markedly characteristic 

 peculiarities of the red blood-cells ( 68). The narrow 

 limits of our work, unfortunately, do not permit us to 

 enter deeper into this very interesting subject ; but we 

 cannot relinquish it without pointing to the probable safe- 

 guard against hybrid impregnation which exists in these Fi mafozoaof P the 

 strongly-marked peculiarities, a kind of aid to the per- sheep, after 

 sistence of distinct species. Besides this, in many animals S^^head- 

 this motion has been missed, while in others a lazy amse- & middle por- 

 boid change of form only could be observed. 



From a chemical point of view the spermatozoa of the mammalia con- 

 sist of a resistent metamorphosed albuminous substance, rich in lime, 

 which approaches in quality to elastin. They withstand for a very long 

 time the process of putrefaction, and even oppose a determined resistance 

 to the action of the mineral acids, dissolving, on the other hand, but still 

 very slowly, in caustic alkalies (Koelliker). Owing to the large propor- 

 tion of mineral ingredients in the spermatozoa, they preserve their form, 

 although subjected to a red heat. 



The composition of pure semen, that is, the secretion of the testicle, 

 was studied many years ago by French*, especially that of the carp, but 

 also of the cock and rabbit. In his observations he found the fluid 

 neutral, resembling a dilute solution of mucus, and containing a certain 

 amount of albumen. Chlorides of the alkalies, and small quantities of 

 phosphates and sulphates of the same, were present in its residual ash, as 

 also phosphate of magnesium. 



The dry substance of the spermatozoa contained 4 -05 per cent, of a 

 yellow matter like butter, probably containing phosphorus, and, we may 

 now add (?), probably also cerebrin and lecithin. Besides this, 5 '21 per 

 cent, of ash constituents, among which lime and phosphoric acid pre- 

 sented themselves. 



Pure semen from the horse has 18*06 of solid ingredients; that of the 

 bull 17 '94, of which the metamorphosed protein substance of the sper- 

 matic filaments amounts to 13'138 per cent, lecithin (?) to 2'165, and 

 mineral matters to 2 '637 per cent. (Koelliker). 



Semen, as discharged from the urethra, is richer in water, from the addi- 

 tion of the secretions of the accessory glands : that of man was found by 

 Vauquelin to contain, on the whole, only 10 per cent, of solid matters. 



The substance which causes semen to coagulate after emission, named 

 long ago by Vauquelin "spermatin," appears to be an albuminate of 

 sodium (Lehmann). 



The development of the spermatozoa was formerly supposed to take place 

 from peculiar cells in the seminiferous tubules. But the process was first 

 accurately described by Koelliker. At the time when semen first begins 



