The Nature of Animal Life. 



fication was a wise one, for in truth, as we shall hereafter 

 see, we know very little about the feelings of the lower 

 organisms. The one animal of whose feelings I know 

 anything definite and at first hand, is myself. Of course, 

 I believe in the feelings of others ; but when we come to 

 very lowly organisms, we really do not know whether 

 they have feelings or not, or, if they do, to what extent 

 they feel. 



Shall we leave this altogether out of account ? Or can 

 we throw it into some form which is more general and less 

 hypothetical ? This, at any rate, we know that all animals, 

 even the lowest, are sensitive to touches, sights, or sounds. 

 It is a matter of common observation that their activities 

 are generally set agoing under the influence of such sugges- 

 tions from without. Perhaps it will be objected that there 

 is no difference between feeling and being sensitive. But 

 I am using the word " sensitive " in a general sense in 

 that sense in which the photographer uses it when he 

 speaks of a sensitive plate, or the chemist when he speaks 

 of a sensitive test. When I say that animals are sensitive, 

 I mean that they answer to touches, or sounds, or other 

 impressions (what are called stimuli) coming from without. 

 They may feel or not ; many of them undoubtedly do. But 

 that is another aspect of the sensitiveness. Using the 

 term, then, with this meaning, we may say, without quali- 

 fication, that all animals are more or less sensitive to 

 external influences. 



8. They are made of " flesh and blood.' 1 Here we have 

 allusion to the materials of which the animal body is com- 

 posed. It is obviously a loose and unsatisfactory statement 

 as it stands. An American is said to have described the 

 difference between vertebrates and insects by saying that 

 the former are composed of flesh and bone, and the latter of 

 skin and squash. But even if we amend the statement that 

 animals are made of " flesh and blood " by the addition of 

 the words, " or of skin and squash," we shall hardly have a 

 sufficiently satisfactory statement of the composition of the 

 animal body. 



