184 ON GENERATION. 



ureters through which the urine distils, a fact which was un- 

 known to Aristotle and philosophers up to this time. In birds 

 and serpents, which have spongy or largely vesicular lungs, the 

 quantity of urine secreted is small, because they drink little, and 

 that by sipping; there was, therefore, no occasion for an urinary 

 bladder in these creatures : the renal secretion, as already 

 stated, is accumulated in a common cavity or cloaca, along with 

 the drier intestinal excrement. Nevertheless, I do find an 

 urinary bladder in the carp and some other fishes. 



In the common fowl the ureters descend from the kidneys, 

 which are situated in long and ample cavities on either side of 

 the back, to terminate in the common cavity or cloaca. Their 

 terminations, however, are so obscure and so hidden by the 

 margin of the cavity, that to discover them from without and 

 pass a fine probe into them would be found impossible. Nor 

 is this at all surprising, because in all, even the largest animals, 

 the insertion of the ureters near the neck of the bladder is so 

 tortuous and obscure, that although the urine distils freely from 

 them into the bladder, and calculi even make their way out of 

 them, still neither fluids nor air can be made to enter them 

 by the use of any amount of force. On the other hand, in 

 birds as well as other animals, a probe or a bristle passed 

 downwards from the kidney towards the bladder by the ureters, 

 readily makes its way into the cloaca or bladder. 



These facts are particularly distinct in the ostrich, in which, 

 besides the external orifice of the common cavity which the 

 velabrum covers, I find another within the anus, having a round 

 and constricted orifice, shutting in some sort in the manner of 

 a sphincter. 



Passing by these particulars, however, let us turn to others 

 that bear more immediately upon our subject. The uterine 

 outlet or vulva, then, or the passage from the common cavity to 

 the uterus of the fowl, is a certain protuberance, soft, lax, 

 wrinkled, and orbicular, resembling the orifice of the prepuce 

 when closed, or appearing as if formed by a prolapse of the in- 

 ternal membrane of the uterus. Now this outlet is situated, as 

 I have said, between the anus and rump, and slightly to the left 

 of the middle line of the body, which Ulysses Aldrovandi ima- 

 gines to be for the purpose of " facilitating intercourse, and the 

 entrance of the genital organ of the cock." I have myself ob- 



