METHODS 111 



mechanism. Reciprocally, the chemical mechanism has 

 its rebound in the colloid mechanism. Analogous relations 

 exist between the mechanism as a whole and the colloid 

 or protoplasmic mechanism. For example, movements 

 of locomotion, which are the easiest to observe among the 

 movements of the mechanism as a whole, are attached 

 by relations of cause and effect to the protoplasmic state 

 of the tissues which compose the limbs. The movement 

 of arms or legs is inseparable from muscular contractions 

 and nervous currents, which are functions of protoplasmic 

 mechanism. In the functions of the mechanism as a whole 

 we shall, therefore, as before have to consider the correspond- 

 ing functions of protoplasmic mechanism ; and it is very 

 certain that, here as there, the exterior circumstances will 

 determine the particular activity of the organism. The 

 only difference is that, instead of acting directly on the 

 protoplasmic mechanism as did the colloid factors B l5 B 2 , 

 B 3 , . . ., the external factors of the action under considera- 

 tion act on the colloid mechanism only through the, inter- 

 mediary of the whole mechanism, which belongs to a higher 

 scale. 



Example. There is a bowl of milk on the table. If 

 I inject the contents of the bowl of milk into the peritoneum 

 of a guinea-pig, I determine directly in the guinea-pig's 

 protoplasm the function (Guinea-pig protoplasm x Milk) 

 a function of protoplasmic mechanism. But a cat 

 arrives before the bowl of milk. The odour arising from it, 

 the light issuing from it, influence the olfactory and visual 

 organs of the cat. The sensorial impressions thus created 

 (by a protoplasmic mechanism which will have to be studied 

 later) transmit a modification to the colloid state of the 

 nerve cells of the brain. This modification is distributed 

 in the different nerve centres along the lines of least resist- 



