CHAPTER V. 
NATURAL SELECTION NOT MANIFESTED IN ORGANIC 
EVOLUTION (continued). 
(c) EMBRYOLOGY. 
“Une échelle des êtres.”—Bonnet. 
Tiie strongest argument in favour of Organic Evolution, 
and the one which supplies the key to all the others, is the 
science of Embryology, which deals with the evolution of 
the individual. The successive stages through which the 
organism passes from the fecundated ovum to the mature 
structure display an increasing complexity. This develop 
ment of the individual organism is regarded as the “abstract 
and brief chronicle ” of the evolution of the race. The 
ontogeny or the history of the development of the indi 
vidual organism, is taken as a proof of the phylogeny or 
the history of the development of the tribe or race from 
which the individual has been derived. It is true that 
there are certain limitations to this principle, but these 
limitations do not in any way militate against the general 
inference in favour of Organic Evolution ; they simply 
modify our views as to the precise details of the develop 
ment which has taken place. Assuming that the develop 
ment of the individual is a reproduction of the evolution 
of the race, and that each individual “climbs up its own 
ancestral tree,” we have now to ask whether we can find 
any trace of the action of Natural Selection in the process