22 Proceedings of the Newport Natural History Society. 
the theory of development, no system can be considered 
satisfactory which leaves out of the question the influence 
of that still obscure force, or group of forces, which has 
long been included in that much discredited term vitalism 
or vitality. The phenomena of vitality are unceasing, and 
the attempt to explain them on purely physical grounds 
has signally failed. It is not necessary to regard “vital 
force ” as a sort of supernatural entity having no relation 
to the other forces of nature; ultimately it will no doubt 
be correlated with the known forces of light, heat, and 
electricity. But, whatever we call it, there is something 
beyond the purely physical forces which distinguishes living 
from dead protoplasm; something beyond heat or electricity 
which determines the functions and the structures of living 
beings. To leave this determining potency out of consid¬ 
eration in treating of the development of organized beings, 
is, I maintain, to fail to take account of one of the chief 
factors in the development of life upon our globe. 
