1 68 THE POPULAR SCIENCE MONTHLY 



restitution of the original bodies brought about. Physical conditions 

 alone determine the direction taken by these "reversible reactions." 

 This phenomenon suggests a possible explanation of the changes taking 

 place in nerve cells and the relation they bear to the production and 

 regulation of the nerve impulse. 



Within the past decade biologists have discovered many facts that 

 throw considerable light on the relation that the nervous system bears 

 to the growth of the organism, and they have also arrived at certain 

 conclusions of great importance in regard to the manner in which nerve 

 cells grow. Portions of living tissues, nerve as well as muscle, or the 

 supporting elements of the body may be removed and grown outside 

 of the animal. Photographs taken at short intervals of nerve cells 

 placed in various artificial media which are kept at the body tempera- 

 ture show a remarkable series of changes. In a comparatively few hours 

 these cells may actually be seen to throw out long processes resembling 

 the embryonic nerves. 



A limited space does not permit more than a passing reference to the 

 advances made, and largely by American investigators in the study of 

 animal behavior. These newer methods of study, says a distinguished 

 English scientist, " contrast with the anecdotal method of the past gen- 

 eration almost as pronouncedly as do modern chemical methods with 

 those of the medieval alchemists." Modern biology with the inspiration 

 derived from the physical and chemical laboratory has already brought 

 new life into the discussion of such old questions as that of variation 

 and inheritance in living beings. To answer the question "What are 

 the traits inherited by our nervous systems ? " we must follow the paths 

 mapped out by the new biology. The way of the statistician has been 

 followed until the new road offered by experiment is within our sight. 



Posterity will, as we have already indicated, measure our intelli- 

 gence by the interest we take in acquiring information in regard to the 

 organs upon the functional development of which depend our continued 

 existence as a race. In the various medical schools and hospitals 

 throughout the country the problems connected with the human brain 

 and nervous system will continue to be subjects that have an immediate 

 claim upon the attention of physicians, but even in these institutions 

 these questions should not be forcibly disassociated from the considera- 

 tion of more fundamental biological phenomena. The possibility of ex- 

 tending the scope of the work carried on in the biological departments 

 of our universities so as to facilitate and encourage investigations in 

 the broad field of biological psychology would be an important factor 

 in bringing these institutions into the closest touch with the subjects of 

 most vital importance to humanity. But in addition a new type of in- 

 stitution dedicated to the study of neuro-biology is greatly needed. The 

 Phipps Psychiatric Clinic in Baltimore will mark a new era in this 



