PAWLOW'S RESEARCHES. 499 



for the purpose, and arrangements made for collecting 

 gastric juice. A sham feeding was followed by the usual 

 results. The left vagus was then rapidly exposed and 

 divided without anaesthesia, and meat again presented to 

 the dog. He devoured it as eagerly as before, but now not 

 a single drop of gastric juice was secreted. After this 

 double division of the vagi, the animal remained in fair 

 condition for three of four days, but during the whole of 

 this time the reflex secretion was absolutely abolished, show- 

 ing that the vagi carry the secretory impulses from the 

 central nervous system to the stomach. At the end of this 

 time digestive troubles supervene. The food remains in the 

 stomach and undergoes putrefaction in consequence of the ab- 

 sence of the normal acid secretion. The dog wastes rapidly 

 anddiesof a species of septicaemia, or of exhaustion consequent 

 on continual vomiting. This mode of death, in consequence 

 of division of both vagi, has also been described by O. Frey. 

 In all cases where we would study the functions of a 

 nerve or nerve centre, we have two experimental criteria 

 to guide us, i.e., abolition of function or paralysis in con- 

 sequence of division of tracts, induced or increased functional 

 activity in consequence of excitation. An application of the 

 second method in the case under discussion confirms the 

 conclusion derived from the effects of section of the vagi. 

 Here, as in dealing with the pancreas, we must take steps 

 to avoid the usual cardio-inhibitory effects of stimulating the 

 vagus. This aim can be attained by dividing the left vagus 

 twenty-four hours before the excitation. I have already 

 mentioned that after this double division of the vagus, the 

 animal remains in a fairly normal condition for two or three 

 days, although there is no secretion of gastric juice. If, 

 however, twenty-four hours alter division of the second 

 vagus, the nerve be drawn out of the wound and stimulated, 

 a secretion of gastric juice is the invariable result. Here, 

 as in the case of the reflex secretion, there is a constant 

 latent period of five to six minutes intervening between the 

 application of the stimulus and the appearance of the first 

 drop of secretion, showing that the delay is due to processes 

 having their seat in the gastric mucous membrane itself. 



35 



