288 ZOOLOGICAL PHILOSOPHY 



preserve their traces or impressions for a longer or shorter period, and 

 finally, by means of these ideas, carry out thought, etc., etc. ? 



It cannot now be doubted that the acts of the intellect are exclusively 

 dependent on organisation, since it is known that even in man dis- 

 turbances in the organs which produce these acts involve others in 

 the acts themselves. 



An investigation of the causes of which I spoke above appears 

 therefore to me to be obviously possible : I have given attention to 

 the subject ; I have devoted myself to an investigation of the only 

 method by which nature can have brought about the phenomena in 

 question ; and it is the result of my meditations on this subject 

 that I am now about to present. 



The essential point is that, in every system of animal organisation, 

 nature has but one method for making the various organs perform 

 their appropriate functions. 



These functions indeed are everywhere the result of the relation 

 between fluids moving in the animal, and the parts of its body which 

 contain these fluids. 



There are everywhere moving fluids (some containable, others 

 uncontainable) which act upon the organs ; and there are also every- 

 where supple parts, which are sometimes in ej-ethism and react on 

 the fluids which affect them, and which are sometimes incapable of 

 reacting ; but in either case they modify the movement of the fluids 

 taking place among them. 



Thus, when the supple parts of organs are capable of being animated 

 by orgasm and of reacting on the contained fluids which affect them, 

 the various resulting movements and changes, both in the fluids and the 

 organs, produce phenomena of organisation which have nothing to do 

 with feeling or inteUigence ; but when the containing parts are so 

 soft as to make them passive and incapable of reacting, the subtle 

 fluid moving in these parts, and modified by them in its movements, 

 gives rise to the phenomena of feeling and intelligence as I shall 

 endeavour to prove in this Part. 



We have therefore to deal only with the relations existing between 

 the concrete supple and containing parts of an animal, and the moving 

 fluids (containable or uncontainable) which act on these parts. 



This well-known fact has been for me ag a beam of light ; it guided 

 me in the research that I have sketched out, and I soon perceived that 

 the intelligent acts of animals are, like their other acts, phenomena 

 of animal organisation, and that they take their origin from the rela- 

 tions existing between certain moving fluids and the organs which 

 produce these wonderful acts. 



What matters it that these fluids, whose extreme tenuity prevents 



