ON GENERATION. 257 



generation and earliest attracts attention is also the first that 

 fails and disappears. 



EXERCISE THE TWENTY-FIRST. 



The inspection after the tenth day. 



All that presents itself on the tenth day is so accurately de- 

 scribed by Aristotle that scarcely anything remains for us to 

 add. Now his opinion, according to my interpretation of it, is 

 this, viz., that "on the tenth daythe entire chick is conspicuous," 1 

 being pellucid and white in every part except the eyes and the 

 venous ramifications. " The head at this time is larger than 

 the whole of the rest of the body; and eyes larger than the head 

 are connected with it," (adhering, and being in some sort ap- 

 pended to the head,) " but having as yet no pupils," (perfectly 

 formed pupils must here be understood, for it is not difficult to 

 make out the distinct tunics of the eye at this epoch;) "the eyes, 

 if removed at this time, will be found as large as beans and black, 

 and if they be incised, a clear humour flows out, cold, and re- 

 fracting the light powerfully, but nothing else," i. e., in the whole 

 head there is nothing but the limpid water which has been 

 mentioned. Such is the state of matters from the seventh to the 

 tenth day, as we have said above. "At the same time," he 

 continues, "the viscera also appear, and all that appertains to 

 the abdomen and intestines," viz., the substance of the heart, 

 the lungs, liver, &c., all of a white colour, mucilaginous, pulpy, 

 without any kind of consistency. " The veins, too, that issue 

 from the heart are already in connexion with the umbilicus, 

 from which one vein extends to the membrane that includes 

 the vitellus, which has now become more liquid and diffluent 

 than it was originally ; another to the membrane which sur- 

 rounds everything," (i. e., the tunica colliquamenti,) " and em- 

 braces the foetus, the vitellus and the interjacent fluid. For 

 the embryo increasing somewhat, one portion of the vitellus is 



Hist. Anirn. lib. vi, cap. 3. 



17 



