LIVING MATTER 69 



nected with the organism which has produced 

 them. 



As an example of the first kind of substance 

 one may instance the bile which is secreted by 

 the liver cells or the pancreatic juice or a number Byc- 

 of the other internal secretions, such as those products 

 of the thyroid body or adrenals, most, if not 

 all of these being of prime importance to the 

 well-being or even existence of the body, but 

 none of them being of first importance to 

 the cells concerned themselves so far as we 

 know. 



The second group of excretions includes the 

 various vegetable oils, and substances such as 

 musk in the animal kingdom. As to these it 

 is difficult, if not impossible, to say that they 

 are of no service to the plant or animal which 

 produces them, and it is only their great value 

 io us which makes us look at them more from 

 our point of view than from that of the organ- 

 ism which produced them. But, at any rate, 

 it is quite clear that the various excreta are 

 got rid of because they are of no further use to 

 the animal excreting them, yet they may be 

 of great service for purposes of fertilising 

 the soil. 



Finally, as regards this question of nutrition 

 and digestion, the result of this taking in of 

 food, and of the changes which take place in 



