158 



HABIT AND INTELLIGENCE. 



[chap. 



Classifica- 

 tion of 

 vegetative 

 fuuctions. 



Animal 

 functions. 



Four 

 grades of 

 the motor 

 function. 



Sponta- 

 neous 

 motion. 



instance, are fotmd alike in the head, in the limbs, and 

 along the spine of man. It is self-evident that the forma- 

 tion of organic compounds must be anterior to any forma- 

 tion of tissues or organs. But it cannot, I think, be said 

 that the formation either of tissues or of organs is in any 

 sense anterior to the other. It is to be remembered also, 

 that, as already stated, there are some tissues, at least in 

 animals, which do not originate in cells, but are formed 

 by the direct transformation of structureless sarcode.^ 



From the point of view which I have taken in the last 

 few paragraphs, the vegetative functions may be clas- 

 sified as 



Formation of organic compounds ; 



Formation of tissue ; and 



Formation of organs : 



of which the first is chemical, and the others may be called 

 structural. 



We now come to the animal functions, which essentially 

 consist in the transformation of energy.^ As I aim only 

 at drawing an outline, not at filling it up (which, indeed, 

 in the present state of science, no one, probably, is com- 

 petent to do), I will say nothing of the production of heat, 

 electricity, and light by animals ; I wUl sj)eak, as I did in 

 the last chapter, only of the motor functions, which are 

 the characteristic ones of unconscious animal life : and of 

 the sensory, conscious, and mental functions. 



In the ascending scale of nature, there are four grades 

 of the motor function, differing from each other according 

 to the circumstances under which the transformation of 

 vital into motor energy is determined. 



The first of these may be called the spontaneous. To 

 this class belong the circrdation, or rather rotation, of the 

 almost fluid contents of vegetable cells, which is often to 

 be seen under the microscope : the motions of the germs 

 of low aquatic organisms, vegetable as well as animal, 

 through the water (which have often caused them to be 



1 P. 127. 



2 See tlie chapter on the Dynamics of Life (Chapter X.) for the relation 

 between conscious nervous action and the transformation of energy. 



