658 THE POPULAR SCIENCE MONTHLY. 



ers. We must place all material coming at second-hand by itself, not 

 as worthless, but as calling for special scrutiny. But so long as we 

 have facts only, we have no science ; such, indeed, are as the wood and 

 stone for the building, and, unless worked up into scientific form, may 

 prove an incumbrance. Let me, then, briefly indicate some of the prob- 

 lems that have seemed to myself and others as most urgently demand- 

 ing solution. 



One of the questions still far from clear is that which we had under 

 discussion last year, viz. : In how far can the lower animals understand 

 man's various forms of expression, especially his spoken words ? A 

 priori, we should not expect that creatures unable to invent words 

 should have the capacity to understand them in the sense in which 

 man himself does. I am inclined to think that more has been claimed 

 for the inferior races of animals in this direction than an exact exami- 

 nation of the subject will warrant. On the other hand, we have proba- 

 bly very much underrated their capacity to Comprehend our various 

 forms of unspoken language. The subject calls for close observation. 

 A kindred problem is the degree to which various kinds of animals 

 can communicate with one another. This is a much more difficult sub- 

 ject, and it may prove that the creatures we despise as so very much 

 inferior may have modes of subtile communication which we are, pos- 

 sibly, incapable even of comprehending. 



The whole subject of the senses of the lower animals is a field for 

 investigation both by the psychologist and the physiologist ; all the 

 more important, as it is scarcely possible to understand one form or 

 degree of sensation adequately, except by comparison with its lower 

 and higher forms. The field is as yet but little tilled, but enough has 

 been done to suggest this very important question : Do the senses of 

 the lower animals and those of man differ only in degree, or also in 

 kind ? Is the sense of smell, e. g., in the dog, merely more acute, or 

 is it not also characteristically different ? The latter seems the more 

 probable, when we consider how different the hearing of man is in some 

 respects (music) from that of other animals, even the dog. 



Among wholly unsolved problems ranks the nature of the mental 

 processes by which many different tribes of animals find their way 

 back to the place from which they have been removed when the dis- 

 tances involved are great, and often when they have never traveled, 

 so much as once the way by which they return. 



Akin to this, possibly, though perhaps quite different, is the ques- 

 tion as to the nature of the faculties by which animals are enabled to 

 migrate. " How a small and tender bird coming from Africa or Spain, 

 after traversing the sea, finds the very same hedge-row in the middle 

 of England, where it made its nest last season, is truly marvelous" 

 (Darwin). We are much in need of more facts in regard to the mi- 

 grations of animals ; and it is hoped that the systematic work recently 

 inaugurated by the American Ornithological Association may lead to 



