564 GENERATION. SECT. XXXIX. 4. 



duction, are foj^ned by the irritations and fenfations, 

 and confequent exertions of the parts previoufly ex- 

 ifting, and to which the new parts are to be at- 

 tached. 



3. In confirmation of thefe ideas it may be ob- 

 ferved, that all the parts of the body endeavour to 

 grow, or to make additional parts to theinfelyes 

 throughout our lives ; but are reftrained by the parts 

 immediately containing them ; thus, if the fkin be 

 taken away, the flefhy parts beneath foon moot out 

 new granulations, called by the vulgar proud flefh. 

 If the periofteum be removed, a fimjlar growth com- 

 mences from the bone. Now in the cafe of the 

 imperfect embryon, the containing or confining parts 

 are not yet fuppofed to be formed, and hence there 

 is nothing to reftrain its growth. 



4. By the parts of the embryon being thus pro- 

 duced by new apportions, many phenomena both 

 of animal and vegetable productions receive an ea- 

 iier explanation ; fuch as that many fetufes are defi- 

 cient at the extremities, as in a finger or a toe, or 

 in the end of the tongue, or in what is called a 

 hare-lip with deficiency of the palate. Por if there 

 fhould bq a. deficiency in the quantity of the firft 

 nutritive particles laid up in the egg for the recep- 

 tion of the firft living filament, the extreme parts, 

 as being lad formed, muft fhe\y this deficiency by 

 their being imperfect. 



This idea of the growth of the embryon accord* 

 alfo with the' production of fome monftrqus girths, 

 which confift of a duplicature of the limbs, as chick- 

 ens with four legs ; which could not occur, if the 

 fetus was formed by the diftentioi} of an original 

 ftamen, or miniature. For if there fhould be a fu- 

 perfluity of the firft nutritive particles laid up in the 

 egg for the firft living filament ; it is eafy to con- 

 ceive, that a duplicature of fome parts may be form- 

 ed. And that fuch fuperfluous nourifhment fome- 



times 



