548 The American Naturalist. [July, 
life. I shall now attempt to show that the facts of evolution, 
while not inconsistent with the idea of continuity of the germ- 
plasm, are wholly at variance with the idea of its independ- 
ence, separation, or isolation from the functions of the body. 
This can be done by proving, first, that the theory of evolution 
solely by natural selection of chance favorable variations in 
the germ-plasm is inadequate ; second, that the inheritance of 
definite changes in the somatic cells is also necessary to evolu- 
tion, and therefore there must exist some form of force or 
matter which connects the activities of the somatoplasm with 
those of the germ-plasm. 
In the following table are placed some of the facts of human 
evolution which we have observed in the first lecture, and as 
they are part of inheritance, they also constitute the main 
external phenomena of heredity : 
Phenomena of Heredity. 
Conserv Neutral. Progressive 
(toward past type). (toward future type). 
a. Repetition of paren- Fortuitous a. Definite Variation 
tal type. in single characters, 
and by accumulation=. 
b. Regression (in b. Definite Variation 
many characters) to Indefinite in many characters 
contemporary race (from contemporary 
type race type). 
. Reversion(mainly Variations. 
in single characters) 
to past race type. 
D 
What are the causes of these various phenomena ? 
Factors of Evolution.—The term “ kinetogenesis ” has been 
applied to the modern form of the Lamarckian theory, for it 
is an application of kinetic or mechanical principles to the 
origin of all structures such as teeth, bone, and muscle. It 
would be fatal to this theory, if it could be shown that the 
