O'SHEA — ASPECTS OF MENTAL ECONOMY. 47 



inference. The plan of construction, as doubtless every one 

 knows, is simple, — a central body or nucleus serving the pur- 

 pose of husbanding resources, as it were; and, radiating out 

 from this are fibers or pathways some of which are designed 

 to convey impressions in the form of sense stimuli to the nucleus 

 of the cell, while others bind into a social union cells in dif- 

 ferent regions of the cerebral community. (See Figs. 1 and 2.) 



The bodies comprising the nucleus of the cell are believed 

 to be of a highly complex and unstable chemical composition, 1 

 in consequence of which they are easily broken down, the 

 energy represented in their union thus being liberated and dis- 

 sipated ultimately in incitement to motor activity, or possibly in 

 thought. Neurology assumes, what was stated above, that all 

 mental and physical action requires for its initiation and main- 

 tenance the liberation of a measure of this mysterious force held 

 in potentia in the nuclei of nerve cells. 



People do not commonly think, in part because they do not 

 reflect upon the matter, that mental activity occurs at the ex- 

 pense of the contents of cerebral cells. Even critical intro- 

 spection reveals thought as a spiritual activity dissociated from 

 or at least not dependent dynamically upon physical processes. 

 It is not easy for me to conceive that my ideas are linked to 

 material agencies, and remain dormant except when these are 

 .active; no matter for present needs which is cause and which 

 -effect. And yet if one will note the physical accompaniments 

 ■of his thinking he will not lack for opportunities to see that 

 arduous mental work requires a comparatively great supply of 

 blood headwards, which is shown in distention of blood ves- 

 sels and in a sense of pressure or strain in the cephalic regions. 

 Every student must have observed also, if he at times becomes 

 attentive to the bodily concomitants of his mental processes 

 (which, let it be said in passing, is a tendency not generally 

 to be nurtured, but rather to be combated) that continued study 

 increases the temperature of the head. 



1 Ladd. Physiological Psychology, pp. 13 and 14, gives the following formulae 

 for some of the substances : protagon, Ci 16 H 2 4i O 3 ^ P. ; cholesterin, C»« H44 

 O + Ha O. 



