322 



STUDIES IN THE EVOLUTION OF ANIMALS 



certain number of cells, it begins to take shape, and layers are 

 formed ; some cells forming muscle, others, nerves, and so on, and 

 ultimately completes a creature like its parents, and this likeness 

 we call heredity. But we know also that sometimes the regular 

 process is disturbed, and monstrous forms are the result, and tera- 



FlG. 96.— (a) First and fifth digits of foot ; [b) Ring and little finger of hand : from 

 Anatomic Pathologique, Tom, 2, Livrais. 38, PL i, of Cruvelhier. 



togenetic investigations may one day tell us something more 

 definite about the genesis of such monstrosities. 



It is curious that most Darwinians infer a great deal regarding 

 the/^j^", from what has gone on in domestic Pigeons, and very few 

 infer anything regarding past phenomena of evolution from the 

 abnormal and monstrous forms \\'hich occur in man and in domestic 

 animals ! 



To conclude : however reluctant we may be to admit it, I believe 

 we shall have to admit that small and gradual accumulations of 

 variations do not cover the whole phenomena before us, and that 

 occasionally large and extraordinary variations may have occurred 

 in the past, which we would now call monstrosities ; and that they 

 may have at times laid the foundation of a new order of progress. 



When once a viable individual with a reproducible monstrosity 



