In common with all the secretions, the saliva is diminished in quantity even when plenty of water is taken, and it frequently becomes acid in reaction. The diastatic ferment is lessened in the mouth, although it can often be isolated from the urine. This, of course, may be produced by the pancreas as well as the solitary glands. In consequence of these changes in the buccal secretions the tongue is somewhat coated, but it is rare to find the heavy coating gradually increasing as the fast progresses, a statement related in connection with those who deprive themselves of food in an effort to cure disease. As most of such cases are subjected to frequent rectal injections it may be surmised that such a foul tongue is an evidence of absorption of toxins from the colon, and the spontaneous clearing of the tongue which is held to be the psychological moment for terminating a long fast may indicate exhaustion of the stored up fat and an increase of acidity due to relative excess or accumulation of amino-acids in the system.

At all events, the administration of food which will call forth the various secretions is sufficient to effect a speedy clearance. Hence it is that milk, which requires no saliva for its digestion, produces a coated, furred tongue, whereas an ordinary diet, especially if vegetable acids such as pineapple juice are included, soon succeeds in dissolving the thick coating. There is no evidence to support the statement made by laymen that it is dangerous to break the fast at any moment. Fasting in the main is really a painless procedure, because, after the first day or so, when a feeling of hunger may manifest itself at meal times, there is no discomfort, and in many cases there is no desire for food even when permission to eat has been obtained. This is an interesting and significant fact, indicating that the appetite is not so much an expression of cell hunger as the result of a local condition of the alimentary canal inciting the individual to regular replenishment. Excessive depletion of the cells interferes with their ability to intimate to the local centres in the mouth and stomach that nutriment is required, and hence there is no appetite.

The secretions of pepsin and hydrochloric acid are both diminished to vanishing point, but the power of immediate secretion in response to the stimulation of food is retained. The unutilised pepsin, or it may be pepsinogen, is frequently absorbed and may be recovered from the urine.

The bile is diminished in quantity, but this is largely due to lack of fluid, because it is decidedly more concentrated. The store of glycogen is rapidly used up at first, but more slowly thereafter. It is, however, capable of being formed anew, and the stores replenished even during fasting.

Faeces continue to be formed and starving animals de-fsecate at least every two or three days. They are composed of the unabsorbable part of the digestive juices, such as cholesterin, bile pigments, mucin, disintegrated epithelial cells from the intestinal mucous membrane, and to a large extent of bacteria. The frequency of evacuation of the bowels varies in man, as in the lower animals. Zuntz records that during a short fast Breithaupt had two motions in six days, well formed, soft yellowish brown, showing under the microscope needle-shaped crystals of fatty acids embedded in a finely granular amorphous substance, in appearance, indeed, similar to those passed on a diet of meat. In this case the average daily quantity amounted to about 9.5 grams, but in other cases an average of 22 grams dried faeces has been reached. The reaction was acid and hydrobilirubin was present. This is quite in accordance with expectation, because hydrobilirubin is simply the refuse of haemoglobin, which continues to be disintegrated even during starvation.

Little albumin is present, but there is a relatively large proportion of nuclein. The nitrogen-content varies from .113 to .316 gram daily with from .44 to 1.35 gram ether extract and .25 to .48 gram ash. The fat is composed partly of free fatty acids and soap and partly of neutral fats and cholesterin. The power of absorption is not diminished during fasting, or even during chronic malnutrition, and putrefaction still goes on, although no protein reaches the colon except what is contained in the epithelial detritus, the inspissated intestinal secretion, and an occasional little haemorrhage which takes place from the bowel wall. The species of bacteria which predominates will determine the nature of the end-product. If the proteolytic bacteria be in the ascendant, indol and skatol will be formed, and it is important to note that these do not come from the breakdown of tissue protein. On the other hand, phenol and skatol will be present if saccharolytic bacteria abound.

Auto-intoxication is therefore quite possible during fasting, and may account not only for the coated tongue but for the presence of indican in the urine.