AND GROWTH. 41 



be fimllar to that by which the mould itfelf is 

 capable of being reproduced ? 



Thelc three queflions include the whole fub- 

 je6l, and appear to depend on one another; for 

 it is impoffible to explain, in a fatisfactory man- 

 ner, the reproduction of animals or vegetables, 

 if we have not a clear idea how the operation 

 of nutrition is performed. Each queftion, there- 

 fore, demands a feparate examination, that we 

 may be enabled to compare their refults. 



The firft, which regards the nature and qua- 

 lities of the nutritive matter, is in part refolvcd 

 by the preceding reafonings, and fhall be clear- 

 ly unfolded in the fubfequent chapters. We 

 fhall fhow, that there are in Nature infinite 

 numbers of living organic particles ; that Nature 

 produces ihem without any expence, becaufe 

 their exiflence is conftant and invariable ; that 

 the caufes of death difunite thefe particles only, 

 but do not deftroy them. Thus the matter 

 aflimilated by an animal or vegetable, is an or- 

 ganic matter of the fame nature with that of 

 the animal or vegetable, and, confequently, may 

 augment the fizc without changing the figure or 

 the qualities of the original moulds; becaufe it 

 has the fame qualities and the fame form with 

 the matter of which the moulds themfelves are 

 compofed. Of the quantity of aliment taken 

 by an animal to fupport its life, and to maintain 

 the vigour of its organs, and of the juices ab- 

 jorbed by the roots and leaves of a plant, a great 



part 



