206 The American Naturulist. [March, 
derant number of individuals which should not possess the 
variation. 
(4) Finally, the characters which define the organic types, 
so far as they are disclosed by paleontology, have commenced 
as minute buds or rudiments, of no value whatsoever in the 
struggle for existence. Natural Selection can only effect the 
survival of characters when they have attained some func- 
tional value. : 
In order to secure the survival of a new character, that is, of 
a new type of organism, it is necessary that the variation 
should appear in a large number of individuals coincidentally 
and successively. It isexceedingly probable that that is what has 
occurred in past geologic ages. We are thus led to look for a 
cause which affects equally many individuals at the same 
time, and continuously. Such causes are found in the chang- 
ing physical conditions that have succeeded each other in the 
past history of our planet, and the changes of organic function 
necessarily produced thereby. 
2 BATHMOGENESIS. 
If we view the phenomena of organic life from the stand- 
‘point of the physicist, the first question that naturally arises m 
the mind is as to the kind of energy of which it is an exhibi- 
tion. Ordinary observation shows that organic bodies perform 
molar movements, and that many of them give out heat. : 
smaller number exhibit emanations of light and electricity. 
Very little consideration is sufficient to show that they include 
among their functions chemical reactions, a conviction which 
is abundantly sustained by researches into the physiology of 
both animals and plants. The phenomena of growth are also 
evidently exhibitions of energy. The term energy is used to 
express the motion of matter, and the building of an embryo 
to maturity is evidently accomplished by the movement z 
matter in certain definite directions. The energy Whi 
accomplishes this feat is, however, none of those which chat- 
acterize inorganic matter, some of which have just been men- 
tioned, but, judging from its phenomena, is of a widely differ- 
ent character. If we further take a broad view of the general 
