PREFA CE. V 



types from common centres. To this extent the 

 theory of evolution may be considered as proved be- 

 yond dispute. In the following pages, therefore, the 

 development of types from centres will be taken for 

 granted. This is the most easily described by the 

 terms development and evolution, and the history of 

 life will therefore be outlined as one of evolution, 

 without implying by the use of this word anything 

 as to the manner of this evolution or as to its philo- 

 sophical significance. 



H. W. CONN. 



MlDDLETOWN, July, 189!. 



