Before concluding his experiments on the agents employed in digestion, Dr Beaumont made many observations with a view to ascertain whether any increase of temperature occurs during that process. By introducing a thermometer with a long stem at the external opening into St Martin’s stomach, both before and during chymification, he succeeded in obtaining very accurate information on this point. In two or three of the experiments the heat of the stomach seemed to be increased after taking food, but in by far the greater number the temperature remained the same. It appears, however, that the variations of the atmosphere produce a sensible change on the heat of the stomach--a dry air increasing and a moist air diminishing it. The ordinary temperature may be estimated at 100° Fahr., and in several instances it was higher at the pyloric than at the cardiac end. On one cloudy, damp, and rainy day, the thermometer rose only to 94°, and on another to 96°; whereas next day, when the weather was clear and dry, it rose to 99°, and on that following, when the weather was both clear and cold, to 100°. On several occasions it rose as high as 102°, and once to 103°; but these were after exercise, which was always observed to cause an increase of two or three degrees. We have already seen that _artificial_ digestion is entirely arrested by cold, and is resumed on raising the temperature to ordinary blood heat. * * * * * Such, then, are the phenomena and conditions of healthy digestion, and such is the light thrown upon them both by the valuable publication of the American physiologist. Before leaving this branch of the subject, however, it may be useful to lay before the reader, as a kind of summary, the principal inferences deduced by Dr Beaumont from his numerous experiments and observations. But in doing so I shall attempt to arrange the results in their natural order; for in the original work they are given without reference either to logical sequence or to time. INFERENCES FROM DR BEAUMONT’S EXPERIMENTS AND OBSERVATIONS.[33] 1. That _hunger_ is the effect of _distention_ of the vessels that secrete the gastric juice. 2. That the processes of _mastication_, _insalivation_, and _deglutition_, in an abstract point of view, do not in any way affect the digestion of the food; or, in other words, when food is introduced directly into the stomach in a finely divided state, without these previous steps, it is as readily and as perfectly digested as when they have been taken. 3. That _saliva_ does not possess the properties of an alimentary solvent. 4. That the _agent_ of chymification is the _gastric juice_. 5. That the pure gastric juice is fluid, _clear and transparent_; without _odour_; a little salt; and perceptibly _acid_. 6. That it contains free _muriatic acid_, and some other active _chemical_ principles.