H. W. MAGOUN 



II 



to the question as to how this study should be carried out and the study 

 itself have become the task of the period following Darwin.' 



Pavlov concluded: 'I have hnished my communication, but I should 

 like to add what seems to me to be of great importance. Exactly half a 

 century ago, ni 1863, was published in Russian the article Reflexes of the 

 Brain, which presented in clear, precise and charming form the funda- 

 mental idea which we have worked out at the present time [see Fig. 3]. 

 What power of creative thought was necessary under the then existing 



Fig. 3 

 Diagram of the central nervous system of the frog (left), from Sechenov (16). Stimulatiiin of 

 the sites marked by crosses inhibited spinal reflexes, illustrating the hierarchy of neural levels 

 and the domination of higher over louder. 



At the right is a diagram of the mechanism of the Pavlovian conditioned reflex (13). The 

 animal makes adaptive adjustments to its environment by means of new links between the 

 cortical analvsers and connections from them to subcortical, unconditioned reflex arcs. 



physiological knowledge of nervous activity to give rise to this idea! 

 After the birth of this idea, it grew and ripened until, in our time, it has 

 become an immense force for directing the contemporary investigation 

 of the brain. Allow me at this fiftieth anniversary of the Reflexes of the 

 Brain to invite your attention to the author, Ivan M. Sechenov, the pride 

 of Russian thought and the Father of Russian physiology!' 



It is interesting to note that Sechenov, like Jackson a contemporary ot 

 both Darwin and Spencer, was more directly influenced by Spencer's 



