NATURAL HISTORY. 
38 
to lay. If left entirely to herself, the hen would seldom lay 
above twenty eggs in the same nest, without attempting to 
hatch them. While she sits, she carefully turns her eggs, 
and even removes them to different situations ; till at length, 
in about three weeks, the young brood begin to give signs of 
a desire to burst their confinement. 
The formation of the embryo is curious. During the first 
day’s incubation, and even when the egg has been under the 
hen a few hours, the head of the chicken may be seen gradu- 
ally uniting itself to the spine of the back. On the second 
day the first processes of the vertebrae may be discerned like 
so many small globules disposed on each side of the spine. 
The first commencement of the wings and the umbilical ves- 
sels may also be distinguished by their dark colour. The 
neck and the breast also shew themselves, and the head con- 
tinues to increase in' size. The third day the whole is more 
distinct and enlarged ; and the heart, which is suspended at 
the opening of the breast, is observed to beat; veins and ar- 
teries may also be perceived about the brains, and the spi- 
nal marrow begins to extend itself through the spine. The 
eyes are considerably formed on the fourth day. The pupil, 
the crystaline and vitreous humours may be distinctly seen. 
The wings increase, the thighs appear, and the whole body 
begins in some degree to be covered with flesh. The fifth day 
the body is covered with a glutinous or unctuous flesh, the 
heart is retained within a very fine membrane, which also ex- 
tends itself all over the breast. The sixth day the spinal mar- 
row, in two divisions, continues to advance along the trunk; 
the liver, which at first was whitish, becomes of a darker 
hue ; both ventricles of the heart beat, aud the body of the 
chicken is covered with skin, in which may be already dis- 
cerned the points of the feathers. The beak may be disco- 
vered on the seventh day, and the brain, the wings, the 
thighs, and even the feet have acquired a perfect form. The 
lungs appear at the end of the ninth day; their colour is 
whitish. On the tenth the muscles of the wings begin to 
form, the feathers continue to shoot out. It is not fill the 
eleventh day that the arteries, which before were separate, 
unite to the heart. The rest of the process consists only in 
an increase and more perfect development of the several 
parts, till they acquire sufficient vigour to break the shell. 
The strongest and best chickens generally are the first can- 
didates for liberty : the weakest come behind, and some even 
die in the shell. When all are produced, the hen leads them 
forth to provide for themselves. Her affection and her pride 
seem then to alter her very nature, and correct her imperfec- 
