10 CLASS AVES. 



The liver turns the bile into the intestines by two 

 conduits^ which alternate with the two or three by 

 which the pancreatic fluid passes. The pancreas of 

 birds is large, but their spleen is small ; they have 

 no epiploon^ the uses of which are in part supplied 

 by the partitions of the air cavities. Two appen- 

 dages are placed toward the origin of the rectum, and 

 a short distance from the anus ; these are more or 

 less long according to the food of the species. The 

 herons have them very short ; other genera, as the 

 pici, are without them altogether. 



The cloaca is a bag in which the rectum, the 

 ureters^ and the spermatic canals, or, in the female, 

 the oviductus, terminate ; it is open externally by the 

 anus. Properly speaking, birds do not urinate, but 

 their urine is mixed with the solid excrement. The 

 ostriches only have the cloaca sufficiently dilated 

 to admit of any accumulation of urine. 



In most of the genera, copulation is effected simply 

 by the juxtaposition of the anus. The ostriches, and 

 many of the web-footed birds, nevertheless have a 

 penis, which has a sort of gutta, or furrow, by which 

 the semen is conducted. The testicles are situate in 

 the interior, above the kidney, and near the lungs ; 

 there is only an ovary and an oviductus. 



The egg, detached from the ovary, where nothing is 

 to be seen of it but the yellow, imbibes, at the top of 

 the oviductus, that exterior liquid called the white, 

 and is furnished with the shell at the bottom of the 

 same canal. Here incubation developes the young, 

 unless when the heat of the climate is sufficient, as 



