see that, exactly five minutes after beginning the feeding, the first drops of juice appear from the stomach, followed by others faster and faster. I catch a couple of drops on the blue litmus paper, and you see that they produce bright red specks on the blue sheet. After thirty minutes' sham feeding we have collected 150 c.c. of juice, which, without filtering, looks as clear and transparent as water. We cannot, therefore, possibly doubt that, when the proper stimulus is used, the gastric glands react to it in a perfectly normal fashion, furnishing a healthy gastric juice. From this it irrefutably follows that only one explanation is to be found for the negative result in the first half of our experiment, viz., that the mucous membrane of the stomach, so far as secretory activity goes, is perfectly indifferent to mechanical excitation. And yet this mechanical stimulus is demonstrated as an exciting agency in the physiological lecture theatre. I venture to think that this lecture experiment from now onwards will quit the field, and give place to the one I have just shown you. This apparently simple experiment of mechanical stimulation can, however, only be successfully performed when certain very obvious rules are followed. These, however, physiologists have not observed, probably on account of a preconceived belief in the effectiveness of the mechanical stimulus. These rules are two. First, it is necessary that the stomach should be clean, and that nothing shall gain entry to it from without. Such conditions were not formerly fulfilled. It is true the stomach was emptied by removing the stopper from the fistular cannula, but it was not washed out till an acid reaction was no longer given, and consequently preformed gastric juice was left behind between the folds of the mucous membrane. At the same time saliva from the cavity of the mouth could gain entry, which quickly became acidified in the incompletely emptied and imperfectly washed-out organ. It is, therefore, not surprising that the glass tube, by setting up contractions of the stomach, was the means of expressing small quantities of acid fluid from the fistula-tube. (The relationship between mechanical stimulation and the motor functions of the stomach is not to be confounded with what we are here speaking of.) That matters are as I state, and that the facts correspond to the explanation is proved by this; namely, that nobody till now has obtained genuinely pure gastric juice of an acidity amounting to 0.5 or 0.6 per cent. It is only necessary to call to mind that Heidenhain, when determining the acidity of the juice first obtained from the resected stomach, was placed in no little doubt as to whether his results (0.5 to 0.6) were correct, and his assistant at the time (Gscheidlen) was set to verify the correctness of his standard solutions. The acidity of the “purest” juice known at that time was scarcely 0.3 per cent. As a further proof that none of the older