STUDIES IN ANIMAL LIFE. 129 



is so because our thoughts are not very precise on 

 the subject of individuality one of the many ab- 

 stractions which remain extremely vague. To jus- 

 tify this application of the word individual to every 

 distinct organ would be difficult in ordinary speech, 

 but in philosophy there is ample warrant for it. 



An organ, in the physiological sense, is an instru- 

 ment whereby certain functions are performed. In 

 the morphological sense, it arises in a differentiation, 

 or setting apart, of a particular portion of the body 

 for the performance of particular functions a group 

 of cells, instead of being an exact repetition of all 

 the other cells, takes on a difference, and becomes 

 distinguished from the rest as an organ.* 



Combining these two meanings, we have the third 

 or philosophical sense of the word, which indicates 

 that every organ is an individual existence, depend- 

 ent more or less upon other organs for its mainte- 

 nance and activity, yet biologically distinct. I do 

 not mean that the heart will live independent of 

 the body at least not for long, although it does 

 continue to live and manifest its vital activity for 

 some time after the animal's death ; and, in the 

 cold-blooded animals, even after removal from the 

 body. Nor do I mean that the legs of an animal 

 will manifest vivacity after amputation, although 

 even the legs of a man are not dead for some time 

 after amputation; and the parts of some of the 

 lower animals are often vigorously independent. 



* See on this point what was said in our first chapter, p. 22. 



F2 



