COMPARATIVE ANATOMY. 



nis, each of which has a bifid point cover- 

 ed with sharp papillae. 



FISHES. 



The male organs of generation possess 

 very different structures in the different 

 orders of this class. We shall take two 

 species as examples ; the torpedo for the 

 cartilaginous, and the carp for the bony 

 fishes. 



In the former instance there are mani- 

 fest testicles, consisting partly of innu- 

 merable glandular and granular bodies, 

 and partly of a substance like the soft roe 

 of bony fishes. We find also vasa defer- 

 cntia, and a vesicula seminalis, which 

 opens into the rectum by means of a 

 small papilla. 



The soft roe supplies the place of testes 

 in the carp, and most other bony fishes. 

 It forms two elongated flat viscera, of a 

 white colour, and irregular tuberculated 

 surface, placed at the sides of the intes- 

 tines and swimming bladder, so that the 

 left encloses the rectum in a kind of 

 groove. Through the middle of each soft 

 roe passes aductus deferens, which opens 

 behind into a kind of vesicula seminalis, 

 and this terminates in the cloaca. 



FEMALE ORGANS OF GENERATION. 



An ovarium is the most essential and 

 universal of all the female parts of gene- 

 ration. In addition to this, those ani- 

 mals which breathe by means of lungs, as 

 well as some fishes, and several white- 

 blooded animals, have, also oviducts, 

 (Fallopian tubes, &c.) or canals leading 

 from the ovarium to the uterus : and last- 

 ly, those, at least, which are impregnated 

 by a real copulation, possess a vagina, or 

 canal connecting the uterus to the ex- 

 ternal organs of generation. 



In birds all the parts which we have 

 just mentioned are single. Some cartila- 

 ginous fishes have two oviducts ; begin- 

 ning, however, by a common opening, 

 and terminating in a simple uterus. The 

 human female, as well as that of many 

 other mammalia, has two ovaria, with an 

 oviduct belonging to each; a simple ute- 

 rus and vagina. The females of this class, 

 in several other instances, possess an 

 uterus bicornis : and in some cases the 

 generative organs are double throughout; 

 that is, there are two uteri, and, at least 

 for some extent, a double vagina. 



Ovaria are found in the females of all 

 animals where the male possesses testi- 

 cles ; but their structure is in general 

 more simple than that of the latter glands, 



particularly in the first tlass. These bo- 

 dies were formerly called the female tes- 

 ticles ; but the term ovary is much pre- 

 ferable, as it denotes the function which 

 the parts perform in the animal econo- 

 my. For, if the office of these bodies be 

 at all dubious, when their structure is 

 considered in man and most of the mam- 

 malia, their organization is so evident in 

 the other classes, that no doubt can be 

 entertained respecting their physiology. 

 It is manifest in all these, that the ovaria 

 serve for the growth and preservation of 

 the germs or ova, which exist in these 

 bodies, completely formed, before the 

 act of copulation. Analogy leads us to 

 conclude that these bodies have the same 

 office in the mammalia ; and thus our ex- 

 planation and illustration of this most in- 

 teresting part of physiology are entirely 

 derived from researches in comparative 

 anatomy. 



Of all the external female sexual or- 

 gans in the mammalia, the clitoris is 

 found the most universally and invariably. 

 It exists even in the whale, and probably 

 is wanting in no other instance than 

 the ornithorhynchus. As its general 

 structure much resembles that of the 

 male penis, it contains a small bone in 

 several species, as the marmota citillus, 

 the racoon, lioness, and sea-otter. 



A true hymen, or one, at least, which in 

 form and situation resembles that of the 

 human subject, has been observed in no 

 other animal. 



The structure and form of the uterus 

 vary very considerably in the mammalia. 

 In no instance does it possess that thick- 

 ness, nor has its parenchyma that density 

 nor toughness, which are observed in the 

 human female. Of those which I have dis- 

 sected, the simia sylvanus had compara- 

 tively the firmest uterus. The two-toed 

 ant-eater came the next in order in this 

 respect. But in the greater number of 

 mammalia, this organ is thin in its coats, 

 resembling an intestine in appearance, 

 and provided with a true muscular cover- 

 ing. 



The variations in the form of the unim- 

 pregnated uterus may be reduced to the 

 following heads : 



1. The simple uterus without horns, 

 (uterus simplex,) which is generally of a 

 pyramidal or oval figure. This is exem- 

 plified in those animals, where we have 

 stated that it possesses thick coats. Its 

 circumference in some simiae presents a. 

 more triangular form than in the wo- 

 man : and towards the upper part, in the 

 neighbourhood of the Fallopian tubes, 



