178 Ornithology. 



thighs appear more soHd; the whole body is covered with a jelly 

 like flesh; the heart that was hitherto exposed, is now covered 

 up within the body, by a very thin transparent membrane; and at 

 the same time, the umbilical vessels, that unite the animal to 

 the yolk, now appear to come forth from the abdomen. After 

 the fifth and sixth days the vessels of the brain begin to be cover- 

 ed over; the wings and the thighs lengthen; the belly is closed up, 

 and turned; the liver is seen within it, very distinctly, not yet 

 grown red, but of a dusky white; both the ventricles of the heart 

 are discerned, as if they were two separate hearts, beating dis- 

 tinctly; the whole body of the animal is covered over, and the 

 traces of the incipient feathers are already to be seen. The 

 seventh day the head appears very large; the brain is entirely 

 covered over; the bill begins to appear betwixt the eyes, and the 

 wings, the thighs, and the legs, have acquired their perfect figure. 

 Hitherto, however, the animal appears as if it had two bodies; 

 the yolk is joined to it by the umbilical vessel that comes from 

 the belly; and is furnished with Its vessels, through which the 

 blood circulates, as through the rest of the body of the chicken, 

 making a bulk greater than that of the animal itself. But towards 

 the end of incubation, the umbilical vessel shortens the yolk, and 

 with it the intestines are thrust up into the body of the chicken 

 by the action of the muscles of the belly, and the two bodies are 

 thus formed into one. During this state, all the organs are found 

 to perform their secretions; the bile is found to be separated, as 

 in grown animals; but it is transparent, and without bitterness; 

 the chicken then also appears to have lungs. On the tenth, the 

 muscles of the wings appear, and the feathers begin to push out. 

 On the eleventh, the heart which hitherto had appeared divided, 

 begins to unite, the arteries which belong to it, join into it, like 

 the fingers into the palm of the hand. All these appearances, 

 come more into view, because the fluids the vessels had hitherto 

 secreted, were more transparent; but as the colour of the fluids 

 deepen, their operations and circulations are more distinctly seen. 

 As the animal thus, by the eleventh day, completely formed, be- 

 gins to gather strength, it becomes more uneasy in its situation, 

 and exerts its animal powers with increasing force. For some 

 time before it is able to break the shell in which it is imprisoned, 

 it is heard to chirrup^ receiving a stijjicient quantity of air for this 

 purpose., from that cavity which lies between the membrane and 

 the shell, and which must contain air to resist the external pressure. 

 At length upon the 20th day, in some birds sooner, and later in 

 others, the enclosed animal breaks the shell within which It has 

 been confined, with its beak; and by repeated efforts, at last pro- 

 cures its enlargement. 



