1894.] _ The Energy of Evolution. 213 
capacity by temperature, humidity, food, ete., thus exhibiting 
physiogenesis. Or changes in the size and form of parts of the 
body may be produced by movements of the organism, or of its 
environment, so displaying Kinetogenesis. So long as these 
modifications of structure should be confined tothe individuals 
thus modified, there would be no evolution. A second genera- 
tion, if not subjected to the same stimuli, would not possess , 
the modifications; and their possession of them would depend 
entirely on the amount of stimulus. In other words there 
would be no accumulation of modification. It has, however, 
been generally believed that these modifications are inherited, 
and I think it can be shown that this belief rests on a 
solid basis. Meanwhile I call the Bathmogenesis which does 
not extend beyond the generation in which it appears, auto- 
bathmogeny. 
The quantitative relation which necessarily exists between 
Bathmism and its sources may be expressed as follows, with 
due recognition of the fact that such expression does not rest 
upon any experimental tests. Statogenesisis work done in the 
construction of tissues like those of the parent and without inter- 
ference. Here we have the molecular energy of the parent 
(either as protozoon or odsperm) temporarily converted in part 
into the molar movements observed to be concomitants of seg- 
mentation; to be represented in the completed tissue by the 
mutual tensions by virtue of which each structural element 
maintains its integrity. It is evidently a process of metamor- 
phosis of energy in which there is less waste than in any other 
known tous. Embryonic growth is accompanied by a very 
slight dissipation of heat, though a slight rise of temperature 
is noticeable in the eggs of cold-blooded animals and in flow- 
ers, when reproduction is active. The products of breaking 
down are equally rare in embryonic growth, and both this and 
the dissipation of heat are evidently largely due to the changes 
wrought in non-cleavable nutritive substances with which the 
yolks are sometimes charged. It is probably to accomplish 
this process that the oxygen necessary for the embryonic 
growth is used. How much loss is due to cell division itself 
