690 ZOOLOGY sect, xvi 



vast amount of work now being done in every department of 

 Zoology. The output of original research is greater than at any 

 former time and is increasing rapidly, and every important addition 

 to our knowledge necessitates a more or less thorough reconsidera- 

 tion of the general and special problems of morphology and 

 classification. Attention, must, however, be drawn to the 

 researches of the last few years in the departments of experimental 

 and statistical Zoology. Exact observations and systematic 

 experiments on comparative physiology, on the precise nature 

 of the action of external conditions, on the physiology of the 

 cell, on the conditions influencing the development and growth of 

 the embryo, on the limits and characteristics of individual 

 variation, and on heredity, are the fields of study in which it 

 may safely be said that the greatest promise of the future lies. 



