1897.] A Chapter in the History of Science. 861 
remote progenitors, and to assume that the atrophy may have 
resulted from a failure of nourishment by the nutrient fluid of 
the organs on account of the loss of functional activity rather 
than to selection by nature of forms with successively dimin- 
ishing eyes. The presence of eyes in most cases certainly 
would scarcely be an element of disadvantage to animals, and 
it may be allowable to invoke some other agency than chance 
selection. We may be justified in postulating that the contin- 
uous disuse of the organs would in time react on the nutrition 
of the parts affected, and finally atrophy or disappearauce 
would result. Like explanation would be applicable to the 
innumerable cases of atrophy of parts known to the naturalist. 
But if cessation of nutrition culminates in final atrophy, in- 
creased nutrition of parts may result in hypertrophy and in- 
creased nutrition may be the concomitant of increased activity 
of parts. The exercise of such parts continued for many gen- 
erations may react on the organization and the progeny at 
length be affected thereby. Of such cases Cope adduced 
many examples. The feet of the horse line furnish illustra- 
tions. The existing horse has the median toes and hoofs 
greatly hypertrophied and the lateral ones atrophied, but the 
Temote ancestors had feet of nearly the same general pattern 
as the rhinoceroses and tapirs. Atrophy of the lateral digits 
has progressed inversely to hypertrophy of the middłe ones. 
An analogous line of development culminating in feet super- 
ficially much like those of the horse was followed by another - 
quite remote family of hoofed mammals, the Prototheriids of 
South America. 
The idea of acceleration and retardation was associated by 
Cope with the idea that the course of evolution was determined 
from the beginning of things, and that life, to use his own 
words, is “ energy directed by sensibility or by a mechanism which 
has originated under the direction of sensibility.” He maintained 
that “ consciousness as well as life preceded organism,” and he 
-called this conception “the hypothesis of archesthetism.” This 
idea I refer to especially because it was broached in his vice- 
presidential address, delivered at the meeting of the American 
