50 



A PRIMER OF BIOLOGY 



is thus a mutual give-and-take between them, the 

 one helping the other. 



Finally, yet another type of nutrition is illustrated 

 by the so-called carnivorous plant which, though 

 green and rooted in the soil and thus in reality in- 

 dependent of organic nutriment, supplements its 

 supplies personally manufactured by absorbing 

 proteids and other organic compounds from insects 

 and other small animals caught by one or other of 

 the various mechanisms with which these carnivorous 

 plants are provided. Many of them possess special 

 digestive glands, and the enzymes produced by them 

 show striking resemblances to those secreted by 

 animals (p. 40). 



Let us now attempt a summary in diagrammatic 

 form of the whole problem of nutrition (Fig. 20). 



H,0 



FIG. 20. 



co t 



Circulation of materials. 



From this diagram it will be seen that kinetic solar 



energy acting on green cells in the presence of carbon 



Circuia- dioxide, water, and simple inorganic salts brings about 



materials, the formation of organic compounds which normally 



would go to the nutrition of the organism possessing 



