CHAP. XX. OF VARIATION AND PROGRESSION. 391 



ture, and from the lowest instincts up to the highest, and, 

 finally, from brute intelligence to the reasoning powers of Man. 

 The improvement in the grade of being had been slow and 

 continuous, and the human race itself was at length evolved 

 out of the most highly organised and endowed of the inferior 

 mammalia. 



In order to explain how, after an indefinite lapse of ages, so 

 many of the lowest grades, of animal or plant, still abounded, 

 he imagined that the germs or rudiments of living things, 

 which he called monads, were continually coming into the 

 world, and that there were different kinds of these monads for 

 each primary division of the animal and vegetable kingdoms. 

 This last hypothesis does not seem essentially different from 

 the old doctrine of equivocal or spontaneous generation ; it 

 is wholly unsupported by any modern experiments or observa 

 tion, and therefore affords us no aid whatever in speculating 

 on the commencement of vital phenomena on the earth. 



Some of the laws which govern the appearance of new 

 varieties were clearly pointed out by Lamarck. He re 

 marked, for example, that as the muscles of the arm become 

 strengthened by exercise or enfeebled by disuse, some organs 

 may in this way, in the course of time, become entirely 

 obsolete, and others previously weak become strong and 

 play a new or more leading part in the organisation of a 

 species. And so with instincts, where animals experience new 

 dangers they become more cautious and cunning, and trans 

 mit these acquired faculties to their posterity. But not 

 satisfied with such legitimate speculations, the French 

 philosopher conceived that by repeated acts of volition 

 animals might acquire new organs and attributes, and that 

 in plants, which could not exert -a will of their own, certain 

 subtle fluids or organising forces might operate so as to 

 work out analogous effects. 



After commenting on these purely imaginary causes, I 



