552 POPULAR SCIENCE MONTHLY. 



lar pattern. The pattern of arrangement of the conductive network of 

 the central organ reveals somewhat of the integrative function of the 

 nervous system. It tells us what organs work together in time. The 

 impulses are led to this and that effector organ, gland or muscle, in 

 accordance with the pattern. The success achieved in the unraveling 

 of the conductive patterns of the brain and cord is shown by the dia- 

 grams furnished by the works of such investigators as Edinger, Exner, 

 Flechsig, van Gehuchten, v. Lenhossek, v. Monakow, Ramon and 

 Schafer. Knowledge of this kind stands high among the neurological 

 advances of our time. 



But we must not be blind to its limitations. The achievement may, 

 though more difficult, be likened to tracing the distribution of blood 

 vessels after Harvey's discovery gave them meaning, but before the 

 vasomotor mechanism was discovered. The blood vessels of an organ 

 may be turgid at one time, constricted almost to obliteration at an- 

 other. With the conductive network of the nervous system the tem- 

 poral changes are even greater, for they extend to absolute withdrawal 

 of nervous influence. Our schemata of the pattern of the great cen- 

 tral organ take no account of temporal data. But the pattern of the 

 web of conductors is not really immutable. Functionally its details 

 change from moment to moment. In any active part it is a web that 

 shifts from one pattern to another, from a first to a second, from a 

 second to a third, then back perhaps to the first and then to a fourth 

 and so on backwards and forwards. As a tap to a kaleidoscope, so a 

 new stimulus that strikes the central organ causes it to assume a par- 

 tially new pattern. The pattern in general remains, but locally the 

 patterns are in constant flux of back and forward change. These time- 

 changes offer, I venture to think, a study important for understanding 

 the integrative function of the nervous system. 



If we regard the nervous system of any higher organism from the 

 broad point of view, a salient feature in its architecture is the follow- 

 ing: At the commencement of every reflex arc is a receptive neurone, 

 extending from the receptive surface to the central nervous organ. 



