34 Animal Life and Intelligence. 



of the cells. While they are all working for the general 

 good of the organism, they are divided into companies, each 

 with a distinct and definite kind of \vork. This is known 

 as the physiological division of labour. It is accompanied 

 by a morphological differentiation of structure. By the 

 form of a cell, therefore, we can generally recognize the 

 kind of work it has to perform. The unstable compounds 

 produced by the various cells must also be different, 

 though not much is known at present on this subject. 

 The unstable compound which forms bone and that which 

 forms the salivary ferment, the unstable matter elaborated 

 by nerve-cells and that built up by muscle-cells, are in 

 all probability different in their chemical nature. Whether 

 the formative plasmogen from which these different sub- 

 stances originate is in all cases the same or in different 

 cases different, we do not know. 



It may, perhaps, seem strange that the products of 

 cellular life should be reached by the roundabout process 

 of first producing a very complex substance out of which 

 is then formed a less complex substance, useful for per- 

 manent purposes, as in bone, or temporary purposes, as 

 in the digestive fluids. It seems a waste of power to build 

 up substances unnecessarily complex and stored with an 

 unnecessarily abundant supply of energy. Still, though 

 we do not know that this course is adopted in all cases, 

 there is no doubt that it is adopted in a great number of 

 instances. And the reason probably is that by this method 

 the organs are enabled to act under the influence of 

 stimuli. They are thus like charged batteries ready to 

 discharge under the influence of the slightest organic touch. 

 In this way, too, is afforded a means by which the organ 

 is not dependent only upon the products of the immediate 

 activity of the protoplasm at the time of action, but can 

 utilize the store laid up during a considerable preceding 

 period. 



Sufficient has now been said to illustrate the nature 

 of the process of life. The fact that I wish to stand out 

 -clearly is that the animal body is stored with large 



