1430 



VESICUL^3 SEMINALES. 



which we shall have to inquire into presently, 

 when we treat of their function. 



The fascia that invests the mass of gyra- 

 tions, like a fusiform bag, contains a great 

 proportion of involuntary muscular fibre, and 

 there is also a large admixture of involuntary 

 fibre in the proper parietes of the tube. It is, 

 of course, lined throughout with a mucous 

 surface, which has a faint reticular marking, 

 like that of the stomach in some animals, 

 and is evidently glandular, or secreting. 



COMPARATIVE ANATOMY. Some consider 

 able difficulty has been experienced by com- 

 parative anatomists in identifying the vesiculte 

 seminales in different animals. This has 

 given rise to much discrepancy as to their 

 existence, or non-existence, in certain species. 

 In the Ruminantia, for instance, the prostate 

 assumes the very singular form of two organs, 

 each having a large central cavity opening 

 into the urethra by a single duct ; and these 

 organs, very naturally, have been regarded by 

 some as vesiculae st-minales. Who, indeed, 

 can undertake to say, with certainty, that 

 they are not ? It is far from improbable that 

 they are both the one and the other pros- 

 tate and vesicula at once. 



There are two very distinct kinds of com- 

 parative anatomical identity functional iden- 

 tify and homological identity. Instances are 

 very numerous of honiologically identical parts 

 being very diverse in function ; the function of 

 the (homological) hand, for instance, is to 

 seize with in man, to walk with in the horse, 

 to fly with in the bat, and to swim with in the 

 whale. And there are not wanting many in- 

 stances of parts functionally identical, and 

 homologically diverse ; a striking instance of 

 which is furnished by the urinary bladder in 

 Mammalia, compared with the reservoir of 

 urine sometimes met with in Ovipara. In 

 the case now before us, the function is in 

 question, and the homology by no means 

 prononce ; no wonder then that identification 

 should be difficult and uncertain. We pro- 

 ceed, however, to notice the various forms 

 of certain sacs met with in brute animals, 

 posited in close relation to the vasa defe- 

 rentia, and impressing one somehow, perhaps 

 homologically, with a notion that they are 

 identical with the human vesiculae seminales. 



Such vesiculae are exclusively confined to 

 the placental division of the Mammalia. They 

 are not met with in the Marsupialia nor 

 Monotremata, nor in the other vertebrate 

 classes, Aves, Reptilia, nor Pisces. In 

 some of these, Aves for instance, there are 

 undoubted reservoirs of semen, formed by di- 

 latations of the vasa dcferentia ; these, how- 

 ever, are manifestly not the organs in question. 



Reservoirs of semen are also met with in 

 some Invertebrate, but since, as I have else- 

 where noticed (Art. SYMMETRY, Vol. IV., 

 p. 850.), homological identity of parts can in 

 no instance be established in animals belonging 

 to different sub-kingdoms, the only identity 

 being in all cases merely that of function, 

 these have no title to be described in an 

 article on the vesiculae seminales, from which 



by function they are, as will be seen here- 

 after, for certain diverse. 



They are indubitably present in all the 

 Quadrumana, the Cheiroptera, and the Insecti- 

 vora. They are wanting in the Carnivora. 

 Present in the Rodentia, and Pachydermata, 

 and in the Manatee. In the other Cetacea 

 they are absent. In the Ruminantia, the ques- 

 tionable organs, mentioned above as hollow 

 prostates, occur. 



In the higher Quadrumana they much re- 

 semble those of man ; and their ducts join 

 the vasa deferentia much in the same manner 

 as in the human subject. In most of the 

 lower monkeys they have not the convoluted 

 form, but occur as simple sacs, and the outlets, 

 at the side of the verumontanum, alone are 

 common to their ducts and the vasa deferentia. 

 In Galeopithecus they are remarkably small. 



In the hedgehog their size is enormous 

 twice that of the vesiculae in man and they 

 have a very, interesting form. They consist 

 each of a small central duct, from which ramify 

 very numerous convoluted caeca of much 

 greater calibre. The central duct terminates 

 on the verumontanum, near the vas deferens. 



In the Rodentia they are, mostly, very large. 

 In the labbit and hare they are, apparently, 

 fused together, and form a single mesial sac, 

 the upper end of which is somewhat square, 

 thick and glandular. This sac opens by a 

 mesial orifice, which receives the vasa defe- 

 rentia, upon the verumontanum. It is, how- 

 ever, very improbable that this really (homo- 

 logically) represents the vesiculae seminales ; 

 its mesial position, between the vasa deferentia, 

 is essentially different from that of the vesiculas, 

 which is always external to those ducts. It is 

 most probably the utriculus prostaticus. In the 

 other Rodents they are double ; long, simple, 

 and bi-fusiform in the guinea pig; serrated in 

 therat; having small ramifications in the agonti; 

 and convoluted in the beaver. In the squirrel 

 they consist of a small tube with glandular 

 parietes, and much convoluted. In the Alpine 

 marmot they are but slightly developed, very 

 convoluted, and have glandular parietes. In 

 all these their outlets are quite distinct from, 

 though near to, those of the vasa deferentia. 



In the Pachydermata they assume very 

 various forms. In the genus Equus they re- 

 semble two small urinary bladders, and have 

 two distinct muscular coats. They are thicker 

 at their fund us than elsewhere; the thickening 

 consisting of a glandular substance. The 

 orifice of their ducts is in common with those 

 of the vasa deferentia. There is also, in this 

 genus, a third vesicular organ, situated me- 

 sially between the vasa deferentia, of a long 

 cylindical form, with a rounded fundus, and 

 secreting a substance of the consistence and 

 colour of honey. This is, undoubtedly, the ho- 

 mologue of the utriculus prostaticus. In the 

 Hyrax they are very large and convoluted. In 

 the Rhinoceros they consist of two large irre- 

 gular sacs, whose excretory ducts join the vasa 

 deferentia. They are very large in the elephant, 

 of an oval figure, with a constriction at their 

 upper end. Their internal surface is divided by 



