COMPARATIVE ANATOMY. 



tion between these cavities ; but after the 

 most diligent search, I think I may ven- 

 ture to assert that there is no such pas- 

 sage. This idea took its rise from there 

 being- no visible opening 1 between the 

 uterus and vagina in the unimpregnated 

 state ; but such an opening being very ap- 

 parent, both during pregnancy and after 

 parturition, overturns this hypothesis ; for 

 we cannot suppose that the foetus, when 

 it has reached the vagina, can pass out in 

 any other way than through the external 

 part." This passage will be facilitated 

 h>y the power which the animal possesses, 

 of drawing down the false belly to the 

 vulva, which has naturally a considerable 

 projection. 



The female organs of generation of 

 birds consist of an ovarium, and an ovi- 

 duct, which opens into the cloaca. Its 

 aperture is placed towards the left of 

 that organ. The tube itself is convolut- 

 ed, somewhat like an intestine. Its inner 

 coat is furnished with numerous papillae. 

 Its diameter is the most considerable at 

 the cloaca, from which it gradually dimi- 

 nishes. It opens towards the abdomen 

 by an expanded orifice, called the in- 

 fundibulum ; which is analogous to 

 the fimbriated orifice of the Fallopian 

 lube. 



The ovarium, resembling in its appear- 

 ance a bunch of grapes, lies under the 

 liver, and contains in a young laying hen 

 about five hundred yolks, varying in size 

 from a pin's head to their perfect mag- 

 nitude : the largest always occupy the 

 external circumference of the part. Each 

 yolk is inclosed in a membrane (calyx) 

 which is joined to the ovarium by means 

 of a short stalk or pedicle (petiolus) A 

 white shining line forms on the calyx 

 when the yolk has attained its complete 

 magnitude. The membrane bursting in 

 tliis part, the contained yolk escapes, and 

 is taken up by the infundibulum in a man- 

 ner which we cannot easily conceive. It 

 then passes along the oviduct, and ac- 

 quires in its passage the white and shell. 

 The calyx, on the contrary, remains con- 

 nected to the ovarium ; but it contracts 

 and diminishes in size, so that in old 

 hens, which have done laying, the whole 

 internal organs of generation nearly dis- 

 appear. 



AMPHIBIA. 



The tortoise has a manifest clitoris 

 lying in the cloaca. The oviduct and 

 ovarium have on the whole much analogy 

 with those of birds ; but all these parts 



are double, and have two openings into 

 the cloaca. 



The frogs of this country have a large 

 uterus, divided by an internal partition 

 into two cavities, from which two long 

 convoluted oviducts arise, and terminate 

 by open orifices at the sides of the heart. 

 The ovaria lie under the liver, so that it 

 is difficult to conceive how the ova get 

 into the above mentioned openings. The 

 uterus opens into the cloaca. 



The toads have not the larg-e uterus ; 

 but their oviducts terminate by a com- 

 mon tube in the cloaca. 



The lizards of this country have on the 

 whole a similar structure to that of the 

 last mentioned animals. Their oviducts 

 are larger, but shorter, and the ovaria 

 contain fewer ova. 



Female serpents have double external 

 openings of the genitals for the recep- 

 tion of the double organs of the male. 

 The oviducts are long and much convo- 

 luted. The ovaria resemble rows of beads 

 composed of yellow vesicles. 



FISHES. 



We shall take the torpedo and the 

 carp as examples of the two chief divi- 

 sions of the class, as we did in speaking- 

 of the male organs. 



In the former fish there are two uteri, 

 communicating with the cloaca by means 

 of a common vagina. The oviducts form 

 one infundibulum, which receives the ova 

 as they sucessively arrive at maturity. 

 These are very large in comparison with 

 those of the bony fishes. The yolk, in 

 its passage through the oviduct, acquires 

 its albumen and shell. The latter is of 

 a horny consistence, and is known by 

 the name of the sea-mouse. It has an 

 elongated quadrangular figure, and its 

 four corners are curved and pointed in 

 the skate, while they form horny plaited 

 eminences in the sharks. The secretion 

 of the albumen, and the formation of the 

 shell, are performed by the papillous in- 

 ternal surface of the duct ; and chiefly 

 by two glandular swellings which appear 

 towards its anterior extremity in the 

 summer months, while the eggs are be- 

 ing laid. 



The structure is much more simple in 

 the carp, and probably also in the other 

 oviparous bony fishes. The two roes oc- 

 cupy the same position as the soft roe of 

 the male does. They are placed at the 

 side of the intestines, liver, and swimming 

 bladder, as far as the anus. They consist 

 of a delicate membrane inclosing the ova, 

 which are all of one size, and extremely 



