S^o G E N $ R A T I O N. SECT. XXXIX. 5 



may however lead to future difcoveries; but certain 

 it is that both the change of the colour of animals 

 to- white in the winters of fnowy countries, and the 

 fpots on birds eggs, muft have fome efficient caufe ; 

 fince the uniformity of their production ftiews it 

 cannot arife from a fortuitous concurrence of cir- 

 cumftances ; and how is this efficient caufe to be 

 detected, or explained, but from its analogy to other 

 animal fads ? 



2. The nutriment fupplied by the female parent 

 in viviparous animals to their young progeny may 

 be divided into three kinds, correfponding with the 

 age of the new creature, i. The nutriment con- 

 tained in the ovum as previoufly prepared for the 

 embryon in the ovary. 2. The liquor amnii pre- 

 pared for the fetus in the uterus, and in which it 

 fwims ; and laftly, the milk prepared in the peclo- 

 ral glands for the new born child. There is reafon 

 to conclude, thaft variety of changes may be pro- 

 duced in the new animal from all thefe iburces of 

 nutriment, but particularly from the firft of them. 



The organs of digeftion and of fanguification in 

 adults, and afterwards thofe of fecretion, prepare 

 or feparate the particles proper for nourifhment 

 from other combinations of matter, or recombine 

 them into new kinds of matter, proper to excite in- 

 to action the filaments, which abforb or attract them 

 by animal appetency. In this procefs we muft at- 

 tend not only to the action of the living filament, 

 which receives a nutritive particle to its bofom, but 

 alfo to the kind of particle, in refpect to form, or 

 fize, or colour, or hardnefs, which is thus previ- 

 oufly prepared for it by. digeftion, fanguificaiion, 

 and fecretion. Now as the firft filament of entity 

 cannot be furnifhcd with the preparative organs 

 above mentioned, the nutritive particles, whiehare 

 at firft to be received by it, are prepared by the 

 'mother; and dcpofned in the ovum ready for its 



reception 



