ACTIONS OF ANIMALS 345 



find it hard to explain how she could have brought feeling into existence, 

 and still harder to conceive how simple relations between material 

 substances can give rise to thought. 



We have just seen that animals, which do not yet possess a nervous 

 system, cannot contain within themselves the force which produces 

 their movements, but that this force must be outside them. Now 

 seeing that the intimate feeling of existence is entirely absent in these 

 animals, and seeing that this feeling is the source of that internal 

 power which produces movements and actions in those that possess 

 it, its privation and the privation of the power resulting from it, 

 necessitate the existence of a force to excite movements, from sources 

 that are altogether external. 



Hence in imperfect animals the force which produces both vital 

 and bodily movements is wholly outside them : they do not even 

 control it ; but they do control to some extent, as I said above, the 

 movements which it impresses on them, and this they do by means of 

 their organisation. 



This force is the result of subtle fluids (such as caloric, electricity, 

 and perhaps others) which incessantly penetrate these animals from 

 the environment, set in motion the visible and contained fluids of their 

 bodies, and by exciting the irritability of their containing parts, give 

 rise to the various movements of contraction which they produce. 



Now these subtle fluids moving incessantly in the interior of their 

 bodies soon carve out special routes which they always follow till 

 new ones are open to them. Hence the similarity of the movements 

 observed in these animals ; and hence again the appearance of an 

 irresistible propensity to carry out movements which, when continued 

 or repeated, give rise to habits. 



As a mere statement of principles is not enough, let us endeavour 

 to elucidate the arguments on which they rest. 



The most imperfect animals, such as the infusorians and especially 

 Monas, only feed by means of absorption which they carry out 

 through the pores of their skin, and by an internal imbibition of the 

 absorbed substances. They have no power of seeking their food nor 

 even of seizing it, but they absorb it because it is in contact with every 

 point of their surface, and the water in which they live provides it in 

 suf&cient abundance. 



These fragile animals, in which the subtle fluids of the environment 

 are the stimulating cause of orgasm, irritabihty, and organic move- 

 ments, carry out, as I have said, movements of contraction which, 

 being incessantly prompted and varied by this stimulating cause, 

 facihtate and hasten the absorptions. Now in these animals the 

 movements of the visible contained fluids are still very slow, and the 



