president's address. 865 



the covering of grass remaining all the time intact, and even the 

 inclination of the slope remaining unchanged. It may well seem 

 incredible to the superficial reasoner that creatures like worms — 

 small, weak, and soft-bodied — should produce such results ; nay, 

 results far greater in the course of time, changing as they do the 

 entire aspect of a country." 



It is this inability, as Darwin well remarks, " to sum up the 

 effects of a continually recurring cause which has often retarded 

 the progress of science, as formerly in the case of Greology, and 

 more recently in that of the principle of evolution." When men 

 like Sir John Herschel or Sir Charles Lyell have spoken of the 

 effects of slowly-acting causes in modifying continents and seas, 

 they have been ridiculed by the thoughtless, who cannot see how 

 the downfall of rain, the slow movement of rivers, the play of 

 waves on shore-lines, can produce such results. In like manner 

 the Biologist is ridiculed who. noting small changes in various 

 races in short periods (or even in periods which to our conceptions 

 seem long), points to the effect of such changes when multiplied 

 during the lapse of those long periods of time of which the earth's 

 crust tells us. But our author has shown how even creatures so 

 tiny and weak as the coral animal have made large islands and 

 long lines of sea-resisting reefs, by constant labour ; and now he 

 shows how under our very feet the despised earthworm is chang- 

 ing the form and nature of the land we live on. When we learn 

 that the rich dark mould in which vegetation thrives best is made 

 by worms, we see that not only the aspect of a country, but the 

 condition of its inhabitants, and even its history, have been 

 modified by their work. So that we may accept in its widest 

 significance his remark that " it may be doubted whether there 

 are many other animals which have played so important a part 

 in the history of the world as have these lowly creatures." 



Mr. Macleay, in his presidential address read before this 

 Society six years ago, drew attention to the importance of study- 

 ing and following out the life history of parasite plants of low 



