112 THE NATURE AND ORIGIN OF LIFE 



ance existing in these centres at the given moment ; and 

 it ends along the centrifugal nerves in a great number of 

 locomotor muscles which contract successively. As a 

 result of all this, the cat approaches the bowl of milk, lowers 

 its head and begins lapping up the contents. 



Here we have something of infinite complexity an 

 activity which it is very difficult to analyse as a whole and 

 which was determined in the cat by the bowl of milk. We 

 have still to observe that the bowl of milk is not alone in 

 this determination ; the state of the surroundings and 

 the state of the cat both play an important part. If the 

 cat had just been fed or saw some one near the bowl of 

 milk armed with a stick, the movements determined would 

 have been quite different. 



In any case, we are forced to verify the fact that the whole 

 cat takes part in the execution of the function we are con- 

 sidering. We cannot assign to the exercise of such a func- 

 tion any organ that does not include the whole cat. The 

 function studied is a page in the history of the cat's activity ; 

 the corresponding organ is the corresponding page in the 

 history of the cat's structural evolution. In the cat, at 

 the given moment, there is a well-defined mechanism 

 different from that which was defined there a moment pre- 

 vious and accomplishing a different thing. In other and 

 rigorously exact language, the living cat is a succession of 

 different organs, all of which we call by the same name 

 " cat " and each of which is a mechanism apart. 



Returning to our notation, we can say that the cat, 

 being a succession of organs A 1? A 2 , A 3 , . . ., exercises succes- 

 sively in conditions B 1} B 2 , B 3 , the successive functions 

 (A x x Bi), (A 2 x B 2 ), (A 3 x B 3 ), . . . And the accom- 

 plishing of the function (A t x BJ transforms cat A t into 

 cat A 2 , which straightway executes the function (A 2 x B 2 ) 



