425 



of correhition tlie action is neitlier quick nor slow; it is to be seen 

 at work wiiere fiinclioiis, tioldiiig llie iiiediuin between tliese two, 

 are concerned. Tlie essential thing liere is, that by nervous stiiiiula- 

 lion substances are set free, wliicli are conducted to other parts ot' 

 the body. 



There is much evidence to lead to the belief that the three forms may finally by 

 reduced to one, but I cannot enter into this here. I have spoken about this possibility 

 already in one of my Herter-Lectures, delivered in New-York in October 1922. 



It may be of importance to lay stress on the fact that the forma- 

 tion of vagus- and sympathicus-substances is not only postulated, 

 but tlint it is proved directly in a physico-cliemical way. 



There is no doubt that an analogous correlation between organs 

 as described here for heart and stomach and for heart and gut will 

 be established also between other organs'). We face here a wide 

 field of new researches; we are only in the beginning. 



May 1923. The Physiological Laboratory of the 



University of Groningen. 



1) So it appeared very recently in our laboratory, that when stimulating the nervus 

 vagus and the nervus sympathicus of the heart, substances are set free, wliich 

 influence the lumen of the small arteries of another animal. (Note after (he 

 correction). 



