ii NEW GERMS 121 



justifiable, and indeed irrational, assump- 

 tion that what must confessedly have 

 happened once can never possibly have 

 happened again, namely, the introduc- 

 tion of new germs with their own special 

 potentialities of development. There 

 are natural divisions in the animal king- 

 dom which seem to suggest the idea of 

 a fresh start on new lines of evolution. 

 The Mammalia may well have been 

 thus begun as a great advance on the 

 hideous Reptiles, which once dominated 

 the world both by land and sea. Fishes 

 may well have had another separate 

 ancestral germ and so with all the 

 lower orders of creation, some of which 

 are very deeply divided from each other. 

 I know of no natural or rational limita- 

 tion on the possibilities of this sugges- 

 tion. On the contrary, the general law 

 of the continuity of Nature is favourable 

 to repetition of any and every precedent 



