NEKVKS OF THE PANCREAS. 59 



easily be understood why, in the ordinary method of operating, accom- 

 panied by the strongest sensory stimulation, and consequently by 

 vascular constriction, even the gland of an animal taken at the height of 

 digestion, often does not yield a single drop of juice. 



Great importance must also be attached to another circumstance 

 which likewise attracted our attention during the investigation. In the 

 experiment just now demonstrated, as also in the " acute" experiment, 

 excitation of the vagus did not call forth the secretion of juice instan- 

 taneously. A certain period of time always elapsed (from fifteen 

 seconds to one minute) between the application of the stimulus and the 

 appearance of the secretory effect. In very many instances the juice 

 began to flow only after the stimulus had already ceased. Finally, one 

 can often observe the following phenomenon (Mett). Suppose the right 

 vagus be excited for a considerable length of time, and thereby a steady 

 flow of juice set up, it is now only necessaiy, without interrupting the 

 stimulus, to excite the other vagus in like manner, when, after a defi- 

 nite often considerable length of time, the secretion is brought to a 

 standstill. All these phenomena have led to the idea that not alone 

 exc'ting influences, but also inhibitory, pass through the vagus to the 

 pancreas. 



With respect to the latter, one is at liberty to make several supposi- 

 tions : they may come into play through the vaso-constrictor nerves of 

 the organ, or through constrictor effects upon the excretory ducts, or, 

 lastly, through genuine inhibitory nerves antagonistic to the secretory. 

 But when it has been proved beyond doubt for several organs that 

 the nerves which regulate them may be classed into two opposing 

 groups, why may not the same be rightly maintained for the glands ? 

 It is quite possible that an antagonism of this nature applies to 

 the genera] principle of innei vation. In the physiological literature of 

 the last few years one may find references here and there to inhibitory 

 innervation of the glands. It appears to me, however, that the question 

 of their existence must be finally decided by a study of the nerves to 

 the stomach and pancreas, because here the inhibitory phenomena are 

 mostly prominently marked. 



Before considering this question more fully, I will now bring forward 

 some experiments dealing with the influence of the sympathetic nervous 

 system upon the secretion of pancreatic juice. They will fuinish us at 

 the same time with material for the discussion of the above subject. 

 The following are the results of the work of Professor Kudrewezki : 



If, in the acute experiment described above, the sympathetic nerve 

 be excited by means of an induced current, a gentle intermittent 

 advance of the secretion is observed, but only during the first few 

 seconds; during the later stages of the excitation, and after its stoppage, 



