On Catagenesis. 971 
for a long time, either by the predominant ues of an organ or by 
| 
the disuse of such part, she preserves by generation among new 
individuals which spring from it, provided the acquired changes 
be common to both sexes or to those which produce new indi- 
viduals.” 
The same proposition was previously enunciated by Lamarck 
in the following condensed form (Recherches sur les Corps vivans, 
p. 50): 
“Tt is not the organ, that is, the nature and form of the parts 
of the body, which have given origin to its habits and peculiar 
functions, but it is, on the contrary, its habits, its manner of life, 
and the circumstances in which individuals from which it came 
found themselves, which have, after a time, constituted the form 
of the body, the number and character of its organs, and the 
functions which it possesses.” 
Several years ago, not having read Lamarck, I characterized 
the above hypothesis as the “ law of use and effort,’! and I have 
subsequently formulated the modus operandi of this law into two 
propositions. The first of these is, that animal structures have 
been produced, directly or indirectly, by animal movements, or 
the doctrine of Ainetogenesis ; the second is, that as animal move- 
ments are primitively determined by sensibility, or consciousness, 
that consciousness has been, and is, one of the primary factors in 
the evolution of animal forms. This is the doctrine of archesthe- 
tism. The doctrine of kinetogenesis is implied in the speculations 
of Lamarck in the following language (Philosophie Zoodlogique, 
Ed. 1830, p. 239): “With regard to the circumstances which 
[nature] uses every day to vary that which she produces, one can 
Say that they are inexhaustible: The principal arise from the 
influence of climates; from diverse temperatures of the atmos- 
phere and of the environment generally ; from diversity of loca- 
tion; from habits, the most. ordinary movements, and most fre- 
quent actions,” &c. The influence of motion on development is 
involved in Spencer’s theory of the origin of vertebrz by strains ;* 
and I have maintained the view that the various agencies in pro- 
ducing change mentioned by Lamarck are in the case of animals, 
simply stimuli to motion’ The immediate mechanical effect of 
, Method of Creation, Proceedings American Philosophical Society, 1871, p- 247- 
ae of Biology, 1, p, 195- ‘ : 
“On the Relation of Animal Motion to Animal Evolution, AMERICAN NATURAL 
IST, Jan., 1878. 
