206 BIRDS. 
The liver pours its bile into the intestine by two ducts, which alternate 
with the two or three through which the pancreatic fluid passes. The 
pancreas of birds is large, but their spleen is small; the omentum is 
wanting; its functions, however, are partly fulfilled by the partitions of 
the air cavities; two blind appendages are situated near the origin of the 
rectum, and at a short distance from the anus; they are longer or shorter, 
according to the regimen of the genus. In the Herons it is short; in 
other genera, that of the Woodpeckers for instance, it is totally deficient. 
The claoca is a pouch, in which the rectum, ureters, spermatic ducts, 
and in the female the oviduct, terminate; it opens externally, by the anus. 
Strictly speaking, Birds do not urinate, as that excretion mingles with 
their solid excrement. In the Ostriches alone, is the cloaca sufficiently 
dilated to allow of an accumulation of the urine. 
In most genera, coition is effected by the simple juxta-position of the 
anus of both; the Ostriches, and several of the Palmipedes, however, 
have a penis furrowed with a groove, through which the semen passes. 
The testes are situated internally above, in the loins, and near the lungs; 
only one oviduct is developed; the other is reduced to a small sac. 
The egg, detached from the ovary, where it consists merely of yolk, 
imbibes that external fluid, called the white, in the upper part of the ovi- 
duct, and becomes invested with its shell at the bottom of the same canal. 
The chick contained within it is developed by incubation, unless the heat 
of the climate suffices for that purpose, as is the case with the egg of the 
Ostrich. The young bird has a little horny point at the extremity of the 
bill, with which it splits open the shell, and which falls off a few days 
after it is hatched. 
The industry and skill exhibited by birds in their variously constructed 
nests, and their tenderness and care in protecting their eggs and young, 
are known to every one; it is the principal part of their instinct. Be- 
sides their rapid transitions through different regions of the air, and the 
vivid and continual action of that element upon them, enable them to an- 
ticipate atmospheric changes, to an extent of which we can form no idea, 
and caused the antients, in their superstition, to attribute to them the 
power of divination. It is unquestionably on this faculty, that depends 
the instinct which acts upon birds of passage, prompting them to seek the 
south on the approach of winter, and the north on the return of spring. 
They do not want either memory, or even imagination—for they dream; 
and all the world knows that they are easily tamed, that they may be 
taught to render various services, and retain the air and words of songs. 
