1 9 4 THE POPULAR SCIENCE MONTHLY. 



mental states, the more intelligible does our inner life become to 

 us. Especially is this true of certain curious phenomena to which 

 our current psychology pays little attention those of automa- 

 tism, suggestibility, and double consciousness as seen in hypnosis, 

 spirit-writing, trance speech, et id genus omne. Not that we are 

 yet in position to explain these phenomena in detail. There is 

 much that defies analysis at our present stage of knowledge, but 

 I have no hesitation in saying that in these dynamic conceptions 

 we have found the key which will in time solve these and many 

 other psychological riddles. 



We know little or nothing of what happens in the brain while 

 we live and move and have our being. In the early days of ex- 

 perimental psychology the physical bases of mental states were 

 crudely conceived as gross movements, either of the nerves them- 

 selves or of some fluid supposed to flow along the nerves and 

 veins to the brain and heart. Nowadays these simpler concep- 

 tions are displaced by theories of chemical activities or molecular 

 vibrations of some kind. For my own part, I am sometimes in- 

 clined to suspect that the true physical basis is none of these, but 

 a disturbance of the same medium that transmits light and heat 

 the ether and to regard the cellular and fibrous structures of 

 the nervous system as a mechanism for producing and transmit- 

 ting these disturbances, much as the battery and wires of an elec- 

 tric circuit produce and transmit that mode of ethereal disturb- 

 ance which we call electricity. However this may be, it is quite 

 certain that the processes which take place in the nervous system 

 are all of one order and are analogous to nay, a part of the phys- 

 ical transformations of energy which we see in the outer world. 

 Their proximate source is the stored-up molecular energy of the 

 food we eat; they are disengaged by the operation of external 

 and internal stimuli ; they can re-enforce or destroy one another ; 

 they can produce extensive muscular, secretory, and nutritive 

 changes in the body. 



Although all of these processes are of essentially the same 

 order in that all taken together form one system of forces, the 

 constitution of every part of which depends for its character upon 

 the constitution of all the coexisting parts, it is probable that con- 

 sciousness is not connected with every part of the system, but 

 only with those processes that take place in the cortex that is, 

 the outer layer of gray matter that covers the surface of the 

 brain. At every moment of conscious life the cortex is the scene 

 of activities so delicate and complex that we can never hope to 

 frame an adequate conception of them. The masses of cells are 

 forever disengaging pulse after pulse of molecular or ethereal 

 disturbance, probably of a vibratory character ; by the countless 

 systems of interlacing fibers these pulses are transmitted from 



