THE SIGNIFICANCE OF TROPISMS 125 



I believe that the investigation of the conditions which produce 

 tropisms may be of importance for psychiatry. If we can call forth in 

 an animal otherwise indifferent to light by means of an acid a helio- 

 tropism which drives it irresistibly into a flame ; if the same thing can 

 be brought about about by means of a secretion of the reproductive 

 glands ; then we have given, I believe, a group of facts, within which the 

 analogies necessary for psychiatry can be experimentally called forth 

 and investigated. 



These experiments may also attain a similar value for ethics. The 

 highest manifestation of ethics, namely, the condition that human 

 beings could be willing to sacrifice their lives for an idea is compre- 

 hensible neither from the utilitarian standpoint nor from that of the 

 categorical imperative. In this case also it might possibly be that under 

 the influence of certain ideas chemical changes, for instance, internal 

 secretions within the body, might be produced which increase the sen- 

 sitiveness to certain stimuli to such an unusual degree that such people 

 become slaves to certain stimuli just as the copepods become slaves to 

 the light. To-day, since Pawlow and his pupils have succeeded in caus- 

 ing the secretion of saliva in the dog by means of optic and acoustic 

 signals, it no longer seems to us so strange that what the philosopher 

 terms an " idea " is a process which can cause chemical activity in 

 the body. 



