- THE STORY OF NINETEENTH-CENTURY SCIENCE 



has been its recognized leader throughout the remainder 

 of the century, is Dr. Wilhelm Wundt, of Leipzig. 



The task was not easy, but, in the long run, it was 

 accomplished. Not alone was it shown that the nerve 

 centre requires a measurable time for its operations, but 

 much was learned as to conditions that modify this 

 time. Thus it was found that different persons vary in 

 the rate of their central nervous activity which ex- 

 plained the " personal equation " that the astronomer 

 Bessel had noted a half-century before. It was found, 

 too, that the rate of activity varies also for the same 

 person under different conditions, becoming retarded, 

 for example, under influence of fatigue, or in case of 

 certain diseases of the brain. All details aside, the es- 

 sential fact emerges, as an experimental demonstration, 

 that the intellectual processes sensation, apperception, 

 volition are linked irrevocably with the activities of 

 the central nervous tissues, and that these activities, like 

 all other physical processes, have a time element. To 

 that old school of psychologists, who scarcely cared 

 more for the human head than for the heels being in- 

 terested only in the mind such a linking of mind and 

 body as was thus demonstrated was naturally disquiet- 

 ing. But whatever the inferences, there was no escap- 

 ing the facts. 



Of course this new movement has not been confined 

 to Germany. Indeed, it had long had exponents else- 

 where. Thus in England, a full century earlier, Dr. 

 Hartley had championed the theory of the close and in- 

 dissoluble dependence of mind upon the brain, and 

 formulated a famous vibration theory of association that 

 still merits careful consideration. Then, too, in France, 

 at the beginning of the century, there was Dr. Cabanis 



414 



