442 



SCIENCE. 



[N. S. Vol. IX. No. 221. 



most interesting of valleys, Clark's Fork of 

 the Yellowstone, still impressed with the 

 many unsolved problems connected with 

 the geology of the range. I at first visited 

 the region in the expectation of finding a 

 partially submerged range of Paleozoic and 

 Mesozoic sediments. If ever such range 

 existed, it bad completely disappeared by 

 profound subsidence. I then looked for the 

 roots of some powerful dominating volcano 

 which had been the source of the varying 

 breccias, but this also I failed to discover. 

 In its stead, if I interpret the facts cor- 

 rectly, I found penetrating the breccias the 

 towering domes and pinnacles of granular 

 and porphyritic rocks, which in some far- 

 distant day, when denudation has removed 

 a greater part of the overlying mass, may 

 be found to form one connected body which 

 erosion has already so far laid bare as to 

 indicate that they all form a part of one 

 broad complex of coarsely crystalline rock 

 of early Tertiary age. 



Arnold Hague. 

 U. S. Geological Survey, Washington, D. C. 



THE PHYSIOLOGICAL BASIS OF MENTAL 

 LIFE* 



If we demand a phj^siological process cor- 

 resjjonding to every possible variation of the 

 content of consciousness the structure of 

 the brain seems far too uniform to furnish 

 a sufficient manifoldness of functions. The 

 mere number of elements cannot be de- 

 cisive ; if they are all functionally coordi- 

 nated they can offer merely the basis for co- 

 ordinated psychical functions. If we have 

 psychical functions of different orders it 

 would not help lis even if we had some 

 millions more of the uniform elements. It 

 would be useless to deny that here exists a 

 great difficulty for our present psj^chology ; 

 the only question is whether this difficulty 

 really opposes the demands and supjDosi- 



*Eea(l before the joint meeting of the Psycho- 

 logical Association and the Physiological Society. 



tions of psychophysical parallelism or 

 whether it means that the usual theories of 

 to-day are inadequate and must be im- 

 proved. It seems to me that the latter is 

 the case, and that hj^potheses can be con- 

 structed by which all demands of psychology 

 can be satisfied withovit the usual sacrifice 

 of consistency. The situation is the follow- 

 ing : 



The whole scheme of the phj'siologists 

 operates to-daj^ in a manifoldness of two 

 dimensions : they tliink the conscious phe- 

 nomena as dependent upon brain excite- 

 ments wliich can vary firstly with regard to 

 their localities and secondly with regard to 

 their quantitative amount. These two 

 variations then correspond to the quality of 

 the mental element and to its intensity. In 

 the acoustical center, for instance, the dif- 

 ferent pitch of the tone sensations corre- 

 sponds to locally different ganglion cells, 

 the different intensities of the same tone 

 sensation to the quantity of the excitement. 

 Association fibers whose functions are not 

 directly accompanied by conscious experi- 

 ences connect these milHons of psychophys- 

 ical elementary centers in a way which is 

 imagined on the model of the peripheral 

 nerve. No serious attempt has been made 

 to ti'anscend this simple scheme. Certainly 

 recent discussions have brought many 

 propositions to replace the simple i^hysio- 

 logical association fiber which connects the 

 psychophysical centers by more complicated 

 systems — theories, for instance, in regard 

 to the opening and closing of the connecting 

 paths or in regard to special association cen- 

 ters or special mediating cell groups — but 

 these and others stick to the old principle 

 that the final psj^chophysical process corre- 

 sponds to the strength and locality of a 

 sensory stimulation or of its equivalent re- 

 production, whatever may have brought 

 about and combined the excitements. 



It is ti-ue that it has been sometimes sug- 

 gested that the same ganglion cell may go 



