INTRODUCTION, 13 
would be as crude as if we attempted to form conclusions 
as to his zoological position without reference to other 
species of animals. 
In the ensuing chapters the following plan has been 
adopted: The effects of increased use and disuse of 
parts is considered in connection with the gradual change 
in the function of organs, and the part played by the 
transmission of the effects of increased use and disuse in 
producing vestigial structures in complex organisms. 
The tendency of vestiges to become diseased or to give 
rise to conditions disadvantageous to the individual is 
fully dealt with. The important and interesting subject of 
the transmission of acquired characters and malforma- 
tions is briefly discussed, and a chapter is devoted to 
causes of disease arising without the organism and the 
relation they bear to the remarkable processes, inflamma- 
tion and fever. Tumours are considered in connection 
with general morbid processes, and the scanty knowledge 
we possess of the zoological distribution of disease is 
summarized. 
