PHYSIOLOGY Ixvii 



mechanical principles, those principles would appear, even 

 at the outset of the discussion, to offer by far the most pro- 

 bable solution. But, in any case, the argument from impossi- 

 bility is one that has no weight whatever. 



I take it that one of the chief values of a historical study 

 such as the present is to establish a comparison between the 

 methods of the past and the methods of the present, so that 

 we may know not only where our ancestors failed, but why 

 they failed, and how we may avoid a similar fate. " Nur 

 durch Werden wird das Gewordene erkannt." In describing 

 Lamarck's physiological philosophy, I shall therefore pay 

 special attention to certain instances of the modern use of 

 the same type of argument, which led in his hands to so 

 miserable a failure. 



Lamarck held that three things are necessary for the 

 constitution of Hfe. There must be the soHd parts of the 

 organism, the liquid parts, and the " exciting cause " of 

 " organic movement." The solid and liquid parts require 

 little illustration. Lamarck describes the solid parts as 

 being " supple " and " containing," and the liquid parts as 

 *' contained." Life is constituted by organic movements, 

 or movements of the contained liquids through the containing 

 solid tissues. The liquids to which he referred were of 

 course the blood and other visible fluids of the organism. 

 But in order to maintain this movement an " exciting cause " 

 or stimulus was needed, and to this exciting cause we must 

 pay further attention. 



Let me do Lamarck the justice to say that he repudiated 

 altogether a " vital principle." "The ancient philosophers," 

 he says, " felt the necessity for a special exciting cause of 

 organic movements ; but not having sufficiently studied 

 nature, they sought it beyond her ; they imagined a vital 

 principle, a perishable soul for animals, and even attributed 

 the same to plants ; thus in place of positive knowledge, 

 which they could not attain from want of observations, they 

 created mere words to which are attached only vague and 

 unreal ideas. 



