THE STUDY OF ANIMALS 5 



such mechanical explanation be possible, that day is far distant, 

 for at present our knowledge of the composition of living substance 

 is exceedingly crude and imperfect. 



Subdivisions of Biology. — So vast a subject as that dealing 

 with life obviously needs subdivision for purposes of convenience, 

 and it is customary to recognize two main branches. Botany and 

 Zoology, dealing with plants and animals respectively (Greek 

 botane, a plant ; zoon, an animal). This does not mean, however, 

 that there is any sharp boundary between the animal and plant 

 worlds. No doubt it is easy to tell the difference between a 

 higher plant and a higher animal, though it might not be so 

 simple to point out in exactly what the difference consists; but 

 when we come to microscopic organisms, difficulties soon arise, 

 and the usual tests break down. Well-defined lines of division 

 but rarely occur in the organic world. 



In this book we shall confine ourself in the main to Zoology, 

 or Natural History as it is often called, but reference to the 

 vegetable kingdom will have to be made in many connections, 

 owing to the obvious fact that there is a very intimate relation 

 between plants and animals. 



Ways of Studying Zoology. — Animals, of course, can be 

 studied from various stand-points, some of which will here be 

 mentioned, as they form a basis for the splitting up of the sub- 

 ject. The accumulated observations of thousands of observers 

 constitute such a mass of knowledge (one, too, that is ever grow- 

 ing), that it is a hopeless task for any individual to acquaint 

 himself with what is already known, and even the professional 

 zoologist can do no more than acquire a general knowledge of his 

 subject, with special knowledge of some limited branch. And 

 when we reflect that, after all, the known is very small, while the 

 unknown is stupendously large, in amount, the present tendency 

 to specialization becomes fully intelligible. It is nevertheless 

 quite easy for anyone of average intelligence to acquire sound 

 general ideas regarding the various possible modes of attacking 

 the subject. 



I. The Stand-point of the Naturalist. — Zoology to the na- 

 turalist is essentially an open-air study. He delights in watching 

 living animals with the view of finding out all he can about their 

 habits, naturally learning at the same time a great deal about their 

 external features, and also finding it necessary to know something 



