LECTURE XL 



THE METABOLISM OF PLANTS (continued). 



THE last two lectures have made us acquainted with the 

 more general facts as to the formation of organic substance 

 and as to the changes which it undergoes in connexion with 

 its distribution in the plant. We will now study the nature 

 of these processes in detail. 



6. The Metabolic Processes. 



Inasmuch as the processes of constructive metabolism 

 have been treated of as fully as our knowledge will allow in 

 a previous lecture (Lect. IX.), we need only repeat here the 

 principal conclusions at which we then arrived. We found 

 that the protoplasm of the plant is capable, under appropriate 

 conditions, of building up more and more complex organic 

 substances from the relatively simple materials of its food, 

 the last of the series of processes being the formation of living 

 protoplasm. Our conception of the nature of this last process 

 will depend upon the view which we take of the nature of 

 protoplasm. If we regard the molecule of protoplasm as a 

 highly complex one containing besides proteid, carbohydrate, 

 fatty, and other radicles, the process in question will be one of 

 remarkable constructive activity : if, on the other hand, we 

 regard protoplasm as simply modified proteid, the process in 

 question will consist essentially in the rearrangement of the 

 radicles in the molecule of proteid (see p. 160). 



