140 EVOLUTION 



formed in some germ-cell of some particular 

 individual, at some point of time." 



The issue at present seems to be this, that 

 there are characters which blend when 

 crossed, and others which segregate when 

 crossed. Patient work is necessary in order 

 to test these two groups and to discover what 

 is the criterion of blending and alternating 

 respectively. In his interesting work on 

 "Hereditary Characters," Dr. Charles E. 

 Walker maintains the thesis that racial 

 characters tend to blend and that individual 

 characters are transmitted in an alternative 

 or Mendelian manner. 



ORIGIN OF VARIATIONS. Since variations 

 form the raw materials of evolution, it 

 would be satisfactory if we could conclude 

 this chapter by stating how they arise. But 

 that is quite impossible at present. We 

 know very little that is certain in regard to 

 the originative factors in evolution. We 

 must still confess, with Darwin: "Our 

 ignorance of the laws of variation is pro- 

 found." It may be of interest, however, to 

 notice some of the suggestions that have 

 been made in regard to this fascinating 

 problem. 



There are variations which mean augmen- 

 tation, or diminution, or re-arrangement of 

 already existing qualities. Now, if the 



