LIVING MATTER 33 



ism. But, secondly, in many cases other sub- 

 stances, which we may speak of as bye-products, are 

 constructed in the course of the operations carried 

 on in the cell-laboratory. These bye-products do 

 not appear to be of primarily or indeed of any im- 

 portance to the cell, and may be actually injurious 

 to it if retained, yet they are or may be highly 

 beneficial or even necessary to other parts of the 

 body, or in other cases they may be of high value to 

 other living creatures, wholly unconnected with the 

 organism which has produced them. 



As an example of the first kind of substance Bye- 

 one may instance the bile which is secreted by the pr 

 liver cells or the pancreatic juice or a number of the 

 other internal secretions, such as those of the 

 thyroid body or adrenals, 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 to us which makes us look at 

 them more from our point of view than from that of 

 the organism which produced them. But, at any rate, 



