BY THE PRESIDENT. 
17 
increased knowledge can lead us to realise the extent of com¬ 
pensatory advantage the species may derive from the successful 
attacks of its enemies. Fas est et ab hoste doceri . Although plants 
and animals are protected, they are not secured against all attacks. 
Immunity from danger is incompatible with development. Each 
species has its Achilles’ heel, which is vulnerable. The petals of 
the chamomile and fever-few are avoided by grazing animals, but 
they are devoured by the chamomile-moth. Nor is every living 
thing solely dependent on itself for protection. Seeds attract birds 
and the birds attract hawks, and in this way the hawks protect the 
seeds. So we find cats feeding on mice, mice destroying humble- 
bees’ nests for the sake of the honey,—the humble-bees that are 
necessary to the fertilisation of the red clover, of which the mice 
eat the seeds. 
What is the explanation of these apparent cross-purposes ? Is 
it not that all the different forms of life with which we are sur¬ 
rounded are directly or indirectly mutually inter-dependent in this 
big universe, and that only now and again does our knowledge 
enable us to recognise the relations that exist between the separate 
links in the great chain of life? We are as ignorant now of the 
services rendered by organisms widely separated from each other, 
as our forefathers were of the mutual dependency between plants 
and insects. No species lives for itself alone, and each species has 
to sacrifice some of its members for another. Nature must ever be 
regarded as a whole. We may commence by limiting our observa¬ 
tion to one particular species, but the further we pursue research, 
the more we shall find the subject of our study to be woven in 
with what we may call collateral issues—issues which are really 
essential conditions. We can discern them, but the knowledge of 
them is not within our reach. The higher we ascend the hill, the 
more we see the extent of regions that we can never hope to tread. 
It was and will be ever thus. The recognition of our ignorance 
?s the measure of our knowledge, and whatever may be the culture 
in time to come of the most learned of mankind, and to whatever 
clearness of intellectual vision they may attain, they will be so 
much the more able than ourselves to realize that they have but 
read a few syllables from the title-page of the Book of Nature. 
VOL. V.—PART I. 
2 
