GASTRIC SECRETION EXCITED BY APPETITE. 71 



at the end of five minutes, and after a further five niinutrs \ve have 

 collected more than I ."> c.e. of tlie fluid; consequently there can be no 

 doubt that in this dog both gistric glands and nerves are uninjured 

 and function in normal manner. At one time we even had a dog \\hich 

 voluntarily took the stones out of one's hand and swallowed them ; the 

 sagacious creature had seen our object in previous experiments ai d 

 learned to perform it of its own accord ! But in tl is case also the, 

 result was negative. 



Clearly, therefore, neither chemical nor mechanical stimulation of 

 the buccal mucous membrane is capable of refiexly exciting the neives 

 of the stomach. Further, it is obvious that the excitation <..f theee 

 nerves in sham feeding is not the result of a stimulation coincidently 

 produced ; that is to say, the excitement of the chewing and swallowing 

 centres does not imply simultaneous action of the secretory centre of 

 the gastric glands. In what, then, does this influence consist which is 

 intrinsic to the sham feeding, but which we have not been able to 

 reproduce in our analytical investigation ? There is only one thing to 

 think of, namely, the eager desire for food, and the feeling of satis- 

 faction and contentment derived from its enjoyment. 



It has, indeed, been known for forty years, thanks to the experiments 

 of Bidder and Schmidt, that at times, the offering of food to a hungry 

 dog, in other words, the excitement of a keen desire for it, is sufficient to 

 cause a flow of gastric juice from the empty stomach. We shall presently 

 have occasion to observe the force of this physiological factor. Here I 

 bring before you another dog, likewise having a gastric fistula with 

 divided oesophagus. The stomach l.as been washed out half an hour ago, 

 and since then not a drop of gastric juice has escaped. We begin to get 

 ready a meal of flesh and sausage before the animal as if we meant to feed 

 it. We take the pieces of flesh from one place, chop them up, and lay 

 them in another, passing them in front of the dog's nose, and so on. 

 The animal, as you see, manifests the liveliest interest in our proceed- 

 ings, stretches and distends itself, endeavours to get out of its cage and 

 come to the food, chatters its teeth together, swallows saliva, and so on. 

 Precisely five minutes after we began to tease the animal in this way the 

 first drops of gastric juice appear in the fistula. The secretion grows 

 ever stronger and stronger, till it flows in a considerable stream. After 

 the lapse of a few minutes we can count the number of cubic centimetres 

 by tens. The meaning of this experiment is . c o clear as to require no 

 explanation; the passionate longing for food, and this alone, has cnlltd 

 forth under our eyes a most intense activity of the gastric glands. If 

 the experiment be frequently repeated, one can easily observe that the 

 keener and moie eager the desire on the part of the dog for the food, the 

 more certain and intense is the secretory effect. In extreme cases 



