
Part II. Sxcv. iii. § 4.) INFLUENCE OF MAN. 473 
life can take place without carrying with it many secondary effects, 
and setting in motion a wide cycle of change and of reaction in the 
-animal and vegetable kingdoms. For example, the incessant warfare 
waged by man against birds and beasts of prey in districts given up 
to the chase leads sometimes to unforeseen results. The weak game 
is allowed to live, which would otherwise be killed off and give more 
room for the healthy remainder. Other animals, which feed perhaps 
on the same materials as the game, are by the same cause permitted 
to live unchecked, and thereby to act as a further hindrance to the 
spread of the protected species. But the indirect results of man’s 
interference with the régime of plants and animals still require much 
prolonged observation.’ 
This necessarily imperfect outline may suffice to indicate how 
important is the place filled by man as a geological agent, and how 
in future ages the traces of his interference may introduce an element 
of difficulty or uncertainty into the study of geological phenomena. 
1 See on the subject of man’s influence on organic nature, the paper by Professor 
Rolleston, quoted in a previous note, and the numerous authorities cited by him. 
