it might be different when it is lodged in the 

 uterus or vagina of the female. 



For reasons given hereafter, I am led to 

 believe that the quantity of actual semen 

 from the testicles emitted at each copulation, 

 is most probably very small, perhaps only 

 three or four drops, at all events not more 

 than the vas deferens is capable of containing. 

 Such an extremely small quantity would be 

 lost in the capacious canal of the urethra, or 

 still more in the enormously capacious canal 

 of the vagina, in the uterus, and in the Fallo- 

 pian tubes. Some dilution, some addition 

 to the volume, seems necessary in order to 

 obtain an efficient injection of the life-giving 

 fluid. And the quantity actually emitted 

 by a man amounts, by all accounts, to two 

 or three drachms. There has been an ad- 

 dition somewhere. The prostate has doubt- 

 less contributed its share, the tiny glands of 

 Cowper theirs, the urethra has given its mite 

 of mucus, more mucus is awaiting in the va- 

 gina, and 1 believe that the vesicuke are not 

 behind in adding a portion of their hoard of 

 ready-formed mucus to the general stock. 

 The spermatozoa huddled and crowded in 

 countless millions in the vas deferens are now 

 able to disport themselves at ease in the con- 

 genial medium ; and the number contained in 

 a few drops of pure semen would be sufficient 

 to people abundantly several drachms of fluid. 



1 am induced by these considerations to 

 form the hypothesis that the office of the 

 vesicular is to secrete, and keep in store, a 

 mucus of such a nature as is congenial to 

 spermatozoa ; which answers the simple 

 purpose of diluting the semen secreted in 

 sparing quantities by the testicles. By di- 

 luting I mean merely increasing the volume, 

 not liquefying; for the mixed fluid is more 

 viscid than pure semen. This hypothesis I 

 would, however, have regarded as only pro- 

 visional until more satisfactory evidence is 

 obtained. It is the only one which the facts 

 at present known warrant. One is much 

 inclined to doubt that so singular an organ as 

 the vesicuke is devoted to so simple a pur- 

 pose. The prostate is generally believed to 

 perform an exactly similar office ; and one is 

 still more loth to believe that two organs so 

 different in appearance as the prostate and 

 vesiculae have an identical function. But as I 

 have advanced this hypothesis I proceed to 

 defend it on these and other points. 



That organs, having the air of being very 

 important, are sometimes engaged in per- 

 forming a very simple and subordinate func- 

 tion, is instanced by the salivary glands, which 

 afford also an example of several distinct 

 organs fulfilling exactly the same purpose : 

 the parotid, the submaxillary, the sublingual, 

 and the numerous little bnccal glands, all 

 entraged in secreting a moistening and diluting 

 fluid, which is not indispensably necessary. 

 All these salivary glands are, however, very 

 much alike in appearance and structure, 

 whilst the vesiculse seminales do not in any 

 way resemble the prostate. In reference to 

 the human subject this remark is true, but 



SEMINALES. 



not as regards many brute animals. In the 

 guinea-pig the prostate is composed of nu- 

 merous ramified caeca, but loosely bound 

 together, and not very small in calibre, and 

 the vesicular really appear as though they 

 were merely a couple of the prostatic caeca, 

 gigantically developed. The secretion of these 

 prostutic cceca is also exactly similar to that 

 of the vesiculae. Objections to the iden- 

 tity of the functions of two organs, based 

 on the difference of their appearance, are 

 completely answered by observing the enor- 

 mous difference of appearance of the liver, 

 for example, in vertebrata, compared with the 

 liver of a crab or lobster ; or, what is more 

 similar to the case under consideration, the 

 large and remarkable gland that secretes the 

 egg-shell in the ray-fish, compared with the 

 part which secretes the egg-shell in birds, 

 which is nothing more than just a peculiar 

 villosity of one portion of the oviduct. It is 

 not now my task to enquire into the function 

 of the prostate, I am merely combatting an 

 objection that may be raised to the hypothesis 

 which I am advocating. 



The question very naturally suggests itself, 

 how is it that the vesiculae are absent in 

 several animals of the mammalian class? In 

 birds and reptiles there is no urethra, no 

 vagina, no uterus for the semen to be lost in : 

 the orifices of the vasa deferentia are brought 

 into immediate apposition with those of the 

 oviducts in the act of copulation ; but in the 

 carnivora, where the vesiculae are indubitably 

 absent, the semen has to find its way, 

 meandering through all those labyrinths; and 

 in the kangaroo, the wombat, &c., the males 

 of which have no vesicula?, the vagina? of the 

 females are remarkably lone, double, and sin- 

 gularly crooked (see Vol. III., fig. 138,). 

 The answer to this is, the males of these 

 animals possess a great number of glands (loc. 

 cit. figs. 135, 136. and Vol. IV. fig. 875.), 

 pouring their secretion into the urethra, 

 which secretion, not improbably, serves the 

 same purpose of dilution. 



With re.ipect to the difference of the con- 

 tents of the vesiculae in different animals, so 

 obvious, for instance, in respect of their con- 

 sistence or viscosity, it should be remembered 

 that we have evidence of a specific relation 

 between the spermatozoa of a given species- 

 and the medium in which they arc destined to 

 float after their exit from the spermatic ap- 

 paratus. I allude to the fact noticed in the 

 article SEMEN (Vol. IV. p. 50-k), that the 

 spermatozoa of a marine non-copulating species 

 continue their movements in sea water, but 

 become instantly motionless and dead when 

 treated with fresh water, which has no inju- 

 rious effect on the spermatozoa of freshwater 

 species. This may, perhaps, also throw light 

 upon the function of other accessory seminal 

 glands. Every copulating species is probably 

 able to supply, from one or several glands, a 

 medium congenial to its own spermatozoa. 



There is then no special reservoir for semen 

 in the human subject, nor in the great ma- 

 jority of mammalian animals. What then 



