86 ANIMAL INDIVIDUALITY [CH. 



determined by the material properties of living sub- 

 stance. There are large cells and small cells, but, 

 with few exceptions (see p. 89), it is a very limited 

 largeness to which even the largest attain. This 

 limitation, depending as it does upon the surface- 

 volume ratio, is one of the primitive, original 

 attributes of the cell ; and to attain size, the cell 

 must in a way do violence to its nature, somehow 

 modifying its surface-tension, overcoming its natural 

 tendency to the spherical, so as to keep its absorptive 

 organ, the surface layer, large enough to supply the 

 demands of the inner mass. 



Why, however, should the cell not be content to 

 stay small what is it to gain from size that it should 

 strive after it ? One is apt to think of size as a rather 

 unimportant element in life. With the example of 

 the field-mouse and the elephant, both built so 

 closely on the same type, the wren and the albatross, 

 one comes to think of a model of organization which 

 can be fitted at will on to whatever bulk of living 

 matter is desired. Within wide limits this is true, no 

 doubt, but limits none the less there are. 



Many Neo-Darwinians ; too, argue that adaptation 

 is the great reality gained by organisms through 

 natural selection, and that, therefore, no one species 

 now alive has preference over any other for to be 

 alive both must be adapted to their surroundings. 

 But to exist and nothing more, to vegetate merely, 



