INTRODUCTION. XX111 



table or animal, are never met with but in 

 minute gelatinous bodies, very supple and 

 delicate ; in a word, only in frail bodies almost 

 without consistence and mostly transparent." 

 These minute bodies he supposes nature 

 forms, in the waters, by the power of attrac- 

 tion ; and that next, subtle and expansive 

 fluids, such as caloric and electricity, pene- 

 trate these bodies, and enlarge the interstices 

 of their agglutinated molecules, so as to form 

 utricular cavities, and so produce irritability 

 and life, followed by a power of absorption, 

 by which they derive nutriment from with- 

 out. 1 



The production of a new organ in one of 

 these, so formed, animal bodies, he ascribes 

 to a new want, which continues to stimulate ; 

 and of a new movement which that want 

 produces and cherishes. 2 He next relates 

 how this can be effected. Body, he observes, 

 being essentially constituted of cellular tissue, 

 this tissue is in some sort the matrix, from 

 the modification of which by the fluids put 

 in motion by the stimulus of desire, mem- 

 branes, fibres, vascular canals, and divers 



1 Anirn. sans Vertebr. i. 174. - Ibid. 181. 



