390 GENERATION. SECT. XXXIX. 4. 3 



their acquiring in their new flate the difference of fex, and the 

 organs of feminal or amatorial reprodu&ion. While the poly- 

 pus, who is their companion in their former flate of life, not 

 being allowed to change his form and element, can only propa- 

 gate like vegetable buds by the fame kind of irritative motions, 

 which produces the growth of his own body, without the femi- 

 nal or amatorial propagation, which requires fenfation ; and 

 which in gnats and tadpoles feems to require a change both of 

 food and refpiration. 



From hence I conclude, that with the acquifition of new parts, 

 new fenfations, and new defires, as well as new powers, are 

 produced ; and this by accretion to the old ones, and not by dif- 

 tention of them. And finally, that the moft eiTential parts of 

 the fyftem, as the brain for the purpofe of diftributing the pow- 

 er of life, and the placenta for the purpofe of oxygenating the 

 blood, and the additional abforbent veiTels for the purpofe of ac- 

 quiring aliment, are firil formed by the irritations above men- 

 tioned, and by the pleafurable fenfations attending thofe irrita- 

 tions, and by the exertions in confequence of painful fenfations, 

 fimilar to thofe of hunger and fuffbcation After thefe an ap- 

 paratus of limbs for future ufes, or for the purpofe of moving 

 the body in its prefent natant flate, and of lungs for future ref- 

 piration, and of teftes for future reprodudlion, are formed by the 

 irritations and fenfations, and confequent exertions of the parts 

 previoufly exifting^ and to which the new parts are to be attached. 



3. In confirmation of thefe ideas it may be obferved, that all 

 the parts of the body endeavour to grow, or to make additional 

 parts to themfelves throughout our lives ; but are reftrained by 

 the parts immediately containing them ; thus, if the fkin be taken 

 away, the flefhy parts beneath foon fhoot out new granulations, 

 called by the vulgar proud flefh. If the periofteum be removed, 

 a fimilar growth commences 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 re- 

 ftram its growth. 



4 By the parts of the embryon being thus produced by new 

 appofitions, many phenomena both of animal and vegetable pro- 

 duftions receive an eafier explanation ; fuch as that many fetuf- 

 es are deficient 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 de- 

 ficiency of the palate. For if there fhould be a deficiency in 

 the quantity of the firft nutritive particles laid up in the egg for 

 the reception of the firft living filament, the extreme parts, as 

 being laft formed, muft fhew this deficiency by their being im- 

 perfeft. 



This 



