320 DARWINISM AND THE PROBLEMS OF LIFE 



parts. On our theory there were four basic particles in 

 the nucleus of this animal, and these would form the 

 four protoplastic sections. Now, if one of these four 

 particles divided into two, and the one resulting particle 

 differed somewhat from the other, we should have five 

 basic particles ; and in the next protozoic cleavage we 

 should have protozoa with cell-bodies containing five 

 different parts. 



We can conceive in this way that the multiplication 

 and differentiation of the basic particles would give rise 

 to more and more complex organisms right up to the 

 vertebrates. The root of the variations is, therefore, 

 in the basic particles. The more complex their com- 

 position becomes, the more highly differentiated will be 

 the organism whose organs they construct during the 

 embryonic development. But we can say nothing very 

 confidently as to the causes of their alteration and 

 multiplication. Weismann, to whom we owe the whole 

 of this theory of heredity, believes that the food that 

 must be supplied to them, as to all organic substance, 

 whether in the nucleus of the ovum or of the protozoon, 

 may vary in quantity from some accident or other, and 

 that a basic particle changes, multiplies, or disappears, 

 according to this variation in its supply of nourishment. 

 With it must vary the section of the body that it 

 builds up. 



Thus the basic particles are never created afresh, but 

 are always formed from pre-existing ones. When they 

 have constructed an organism, their variations come to 

 light in it and in the struggle for life, because the form 

 of the particular organism is changed in harmony with 



