688 Studies in the Theory of Descent. 



the birth and growth of the individual would 

 be able to take place without the continuous en- 

 croachment of the environment, such as occurs 

 in nutrition and respiration. Now this is known 

 to be impossible, so that those who support the 

 existence of such a force, if any still exist, would 

 be driven to the obscure idea of a co-operation 

 between the designing power and the influences 

 of the environment, just in the 'same manner as 

 such a co-operation is at present postulated by 

 the defenders of the phyletic vital force. I shall 

 further on take the opportunity of pointing out 

 that this last idea is quite untenable; with respect 

 to the (ontogenetic) vital force any clearer proof 

 cannot well be adduced, but it will be admitted 

 that the confused notion of the co-operation and 

 inter-action of teleological and causal powers is, 

 from our point of view, opposed to those very 

 simple and clear ideas which are in harmony with 

 the views on phyletic development. As in racial 

 development each change of the organic type is 

 entirely dependent upon the action of the environ- 

 ment upon the organism, so in the development 

 of the individual, the totality of the phenomena of 

 the personal life must depend upon similar actions. 

 Physiology, as is known, herein entirely supports 

 our view, since this shows that without the con- 

 tinual alternating action of the environment and 

 of the organism there can be no life, and that 

 vital phenomena are nothing but the reactions of 



