EFFECTS Otf DIRECT EXCITATION OF THE VAGtTS. 55 



to an hour or more. If, after the nerve began to work, the stimulus 

 were removed, the secretory effect disappeared only gradually, to return 

 however, and this time with rapidity, if the stimulus were reapplied a 

 few minutes later. The administration of a drug such as atropin, which 

 restrains secretion, destroys the irritability of the nerves. 



The existence of so lengthened a period during which stimulation 

 of the nerves gives no result may be explained, in the first instance, on 

 the ground that the shock of the operation depressed the excitability of 

 the gastric glands. It can, however, be explained in another and 

 more likely way. We have already remarked that sham feeding, very 

 soon after the anaesthetic, gives a perfectly normal secretion of juice, 

 and yet the period of latency is quite as long in this form of experi- 

 ment with narcosis as without it. It is hardly conceivable that the 

 operation, notwithstanding the narcosis and the division of the spinal 

 cord, exercised any important reflex inhibitory influence on the gastric 

 glands. We are forced to conclude, therefore, that in artificially stimu- 

 lating the vagus, both exciting as well as restraining impulses are 

 transmitted to the glands. This view would find its simplest expression 

 in a hypothesis which assumes the presence of inhibitory nerves acting 

 in antagonism to the secretory, in a manner similar to what we already 

 know exists in the innervation of the heart, the vessels and other organs. 

 This hypothesis will be more fully discussed in connection with the 

 pancreas, where we shall find ourselves in possession of a series of appro- 

 priate facts and, indeed, of direct proofs recently established. 



From both forms of experiment, therefore, the chronic as well as the 

 acute, we are fully justified in concluding that the vagus nerve contains 

 secretory fibres for the gastric glands. It is necessai-y to repeat, 

 however, that one must not infer that the integrity of the vagus is the 

 only requisite condition for the secretory work of the stomach. Many 

 previous investigators, and we ourselves as well, have been convinced 

 that the stomach is capable of preparing its specific secretion in the 

 absence of vagus influence. Naturally the work of secretion under 

 these conditions deviates not inconsiderably from the normal, both as 

 regards the commencement of the flow as well as the product formed. 

 Whether this secretion, which occurs after the vagi are severed, is to be 

 ascribed to the action of the sympathetic nerves or to some other 

 agency cannot for the present be decided. Furthermore, Professor 

 Ssanozki has been able to verify the inhibitory effects of atropin, in a 

 perfectly convincing manner, on a dog with Heiclenhain's resected 

 stomach, and therefore with the vagus fibres divided. Atropin, how- 

 ever, paralyses secretory nerve mechanisms in a very special manner, 

 and we must hope that further investigations into the woi'k of the sympa- 

 thetic nervous system now that we know the relationship between 



