ANIMALS. 171 



piete work of nature, in which so much is left for accident to finish or 

 destroy. 



But however inferior this kind of generation may be, the observa 

 tion of it will afford great insight into that of nobler animals, as we 

 can here watch the progress of the growing embryo, in every period 

 of its existence, and catch it in those very moments when it first seeim 

 stealing into motion. Malpighi and Haller have been particularly in 

 dustrious on this subject ; and, with a patience almost equalling that 

 of the sitting hen, have attended incubation in all its stages. From 

 them, therefore, we have an amazing history of the chicken in the 

 egg, and of its advances into complete formation. 



It would be methodically tedious to describe those parts of the egg 

 which are well known and obvious ; such as its shell, its white, and its 

 yolk ; but the disposition of these is not so apparent. Immediately 

 under the shell lies that common membrane, or skin, which lines it on 

 the inside, adhering closely to it every where, except at the broad 

 end, where a little cavity is left, that is filled with air, which increases 

 as the animal within grows larger. Under this membrane are con 

 tained two whites, though seeming to us to be only one, each wrapped 

 up in a membrane of its own, one white within the other. In the 

 midst of all is the yolk, wrapt round likewise in its own membrane. 

 At each end of this are two ligaments, called chalaza;, which are, as 

 it were, the poles of this microcosm, being white dense substances, 

 made from the membranes, and serving to keep the white and the 

 yolk in their places. It was the opinion of Mr. Derham that they 

 served also for another purpose ; for a line being drawn from one 

 ligament to the other, would not pass directly through the middle of 

 the yolk, but rather towards one side, and would divide the yolk into 

 two unequal parts, by which means these ligaments served to keep 

 the smallest side of the yolk always uppermost ; and in this part he 

 supposed the cicatricula, or first speck of life, to reside ; which, by 

 being uppermost, and consequently next the hen, would be thus in the 

 warmest situation. But this is rather fanciful than true, the incipient 

 animal being found in all situations, and not particularly influenced by 

 any.* The cicatricula, which is the part where the animal first begins 

 to "show signs of life, is not unlike a vetch, or a lentil, lying on one 

 side of the yolk, and within its membrane. All these contribute to 

 the little animal's convenience, or support ; the outer membranes, and 

 ligaments, preserve the fluids in their proper places; the white serves 

 as nourishment ; and the yolk, with its membranes, after a time, be- 

 comes a part of the animal's body.t This is the description of a hen's 

 egg, and answers to that of all others, how large or how small 

 soever. 



Previous to putting the eggs to the hen, our philosophers first ex- 

 amined the cicatricula, or little spot, already mentioned ; and which 

 may be considered as the most important part of the egg. This was 

 found, in those that were impregnated by the cock, to be large; but, 

 in those laid without the cock, very small. It was found, by the mi- 

 croscope to be a kind of bag, containing a transparent liquor, in tnn 



Ballet. t Ibid 



