ON GENERATION. 455 



surround. The outer of the two common membranes which 

 adheres to the shell is the firmer, that it may take no injury 

 from the shell ; the inner one again is smooth and soft, that it 

 may not hurt the fluids ; in the same way, therefore, as the 

 meninges of the brain protect it from the roughness of the 

 superincumbent skull. The internal membranes, as I have 

 said, include and keep separate their peculiar fluids, whence 

 they are extremely thin, pellucid, and easily torn. 



Fabricius ascribes great eminence and dignity to the chalazse, 

 regarding them as the parts whence the chick is formed ; he, 

 however, leaves the spot or cicatricula connected with the mem- 

 brana vitelli without any office whatsoever, looking on it merely 

 as the remains of the peduncle whence the vitellus was detached 

 from the vitellarium in the superior uterus of the hen. In his 

 view the vitellus formerly obtained its nourishment either by 

 this peduncle or the vessels passing through it ; but when de- 

 tached, and no longer nourished by the hen, a simple trace of 

 the former connexion and important function alone remains. 



I however am of opinion that the uses of the chalazse are no 

 other than those I have assigned them, namely, that they serve 

 as poles to the microcosm of the egg, and are the association of 

 all the membranes convoluted and twisted together, by which not 

 only are the several fluids kept in their places, but also in their 

 distinct relative positions. But I have absolute assurance that 

 the spot or cicatricula in question is of the very highest im- 

 portance; it is the part in which the calor insitus nestles; 

 where the first spark of the vital principle is kindled ; for the 

 sake of which, in a word, the whole of the rest of the fluids 

 and all the membranes of the egg are contrived. But this has 

 been already insisted on above. 



Formerly, indeed, I did think with Fabricius that this cica- 

 tricula was the remains or trace of the detached peduncle ; but 

 I afterwards learned by more accurate observation that this was 

 not the case ; that the peduncle, by which the vitellus hangs, 

 was infixed in no such limited space as we find it in apples and 

 plums, and in such a way as would have given rise to a scar 

 on its separation. This peduncle, in short, expands like a 

 tube from the ovary on towards the vitellus, the horizon of 

 which it embraces in a bipartite semicircle, not otherwise than 

 the tunica conjunctiva embraces the eye ; and this in suchwise 



