186 SENSATION, IDEATION, 



Will go to constitute the mental state ; and it is only by 

 scientific abstraction that we are able to analyze the state 

 into elements which are never really existent but in 

 mutual combination. These elements are found, indeed, 

 in very various proportions in different states sometimes 

 one preponderates and sometimes another ; but there is 

 no state in which they are not all co-existent." Similar 

 views have been even more prominently urged by Herbert 

 Spencer, and they are, moreover, fully in accordance with 

 his general notion that "the highest forms of psychical 

 activity arise little by little out of the lowest, and cannot 

 be definitely separated from them." * 



But why, it may be asked, should progress be observed 

 in the development of the Perceptive Powers and all that 

 this includes, as we pass from lower to higher animals ? 

 and what evidence have we that the acquirements and sus- 

 ceptibilities of one generation of animals are handed down 

 to the next, to be by them improved upon and transmitted 

 in turn ? These all-important questions now need our 

 brief but earnest attention. 



Life is aptly described in general terms by Herbert 

 Spencer, as " the continuous adaptation of internal to 

 external conditions." Nerve tissues and organs are, as 

 we have seen reason to believe, at once the result of this 

 sorrespondence, and the means whereby it becomes organ- 

 ically registered. And as mental phenomena are held to 

 result from the actions of this registering mechanism, they 

 must necessarily show something of that continuity which 

 exists in the mechanism itself. As the degree of corre- 

 spondence between the organism and its surroundings 

 increases, the sum total of mental phenomena must be 



* See " Principles of Physiology," vol. ii. pp. 512-516. 



