INTRODUCTION. 
THIs volume is not intended exclusively for either 
medical men or biologists, but for all who take an 
interest in the modern speculations inseparably 
bound up with the present position of biological 
science. 
The first five of the six articles now published 
together, although they have been written at differ- 
ent periods and with different objects in view, are 
devoted to subjects more or less cognate. So that 
one will be found to illustrate allusions made in 
others. 
The conception which it is sought to defend in 
the address “On the Evolutions of Organization ” is 
that these evolutions are definite, and that the high- 
est evolution of animal life is completed in man. 
Development both in the individual and in the 
totality of life is not only a development from a 
simple beginning, but a development towards a 
completed whole. There is morphological design, 
and when in any line of development the design is 
