70 THK WORK OF THE DIGESTIVE GLANDS. 



every conceivable form of stimulus which could possibly come into play 

 in the act of ea.ting, and yet would not obtain the slightest indica- 

 tion of secretory activity in the stomach. In this dog with a gastric 

 fistula, and with also a divided oesophagus, I will try such an experi- 

 ment, using the most effective chemical stimulus to the buccal mucous 

 membrane, viz., acid solution. 



The secretion of saliva begins at once, as you see ; the acid is, 

 therefore, effective. From the stomach, however, in spite of continued 

 excitation, no secretion results, although the acid, mixed with the saliva., 

 is swallowed and Hows out again from the upper segment of the oeso- 

 phagus that is to say, passes along precisely the same path that the 

 food takes in sham feeding. 



We could experiment in the same way with a number of other 

 substances: saline, bitters, pepper (strong local excitation), mustard, 

 and so on, and always with the same results ; a free secretion of saliva, 

 but perfect quiescence of the gastric glands. We may even, with the 

 same object, employ the soluble constituents of flesh in the form of a 

 decoction, and likewise observe, in most cases at least, no sign of activity 

 on the part of the gastric glands. 



With the chemical we may also combine a mechanical stimulus. We 

 can, for example, wipe out the mouth with a sponge soaked in the 

 solution to be experimented with, but always with the same negative 

 result. We may finally give such pieces of sponge, or even smooth 

 stones of considerable size, to the dog to swallow, passing them back 

 behind the anterior pillars of the fauces and allowing them to fall out 

 again, from the upper portion of oesophagus. It may be added that a 

 well-taught dog puts up with all these procedures without the slightest 

 protest. You see that all the manipulations in this case are carried 

 out with bare hands and without instrumental aid. One can easily 

 train a clog to swallow etones which are placed in the anterior part of 

 the buccal cavity. It simply makes a few chewing movements and 

 swallows them down. The dog on which the acid experiment has just 

 been made serves also for the swallowing of the stones. The attendant 

 now places some pebbles iri the front part of the mcmth, when the 

 animal rolls them round, as if chewing and gnawing them, and then 

 swallows them. The stones fall out, as you see, from the oesophagus, 

 and drop with an audible sound upon the table. This play with the 

 stones has now lasted fifteen or twenty minutes (in the laboratory we 

 have often kept it up for hours), and yet not a drop of gastric juice is 

 to be seen. 



In order to prove that the dog is perfectly healthy and normal, we 

 lay aside the stones and proceed to our old experiment of sham feeding. 

 As you see, the first drop of gastric juice makes its appearance precisely 



