Its absence from the pancreatic juice of infants is an indication that starch should not be given them.  Another ferment, stearopsin, emulsifies fats.  The bile is alkaline and assists the pancreatic juice in neutralising the acid mixture that leaves the stomach; it also assists the absorption of fats.  The digestion of proteids is not completed in the stomach.  There are some who look upon the stomach as chiefly of use as a receptacle for the large mass of food, which is too quickly eaten to be passed at once into the intestines; the food being gradually expelled from the stomach, in such quantities as the duodenal digestion can adequately treat.  A frequently used table, showing the time required for the digestion of various foods in the stomach, is of little practical value.  There is ample provision for the digestion of food, there is a duplication of ferments for the proteids and starch.  In health, the ferments are not only very active, but are secreted in ample quantities.  The digestive or unorganised ferments must not be confused with the organised ferments such as yeast.  The latter are living vegetable cells, capable of indefinite multiplication.  The former are soluble bodies, and though capable of transforming or digesting some thousands of times their mass of food, their power in this direction is restricted within definite limits.  Another and preferable name for them is enzymes.

The action of saliva on starch is powerfully retarded by tea, this is due to the tannin.  Coffee and cocoa are without effect.  Tea infused for two minutes only, was not found to have sensibly less restraining effect than when infused for thirty minutes.  On peptic digestion both tea and coffee had a powerful retarding effect.  When of equal strength cocoa was nearly as bad, but as it is usually taken much weaker, its inhibitory effect is of little consequence.

Bacteria are minute vegetable organisms, which exist in the dust of the air, in water and almost everywhere on or near the surface of the earth.  They are consequently taken in with our food.  They exist in the mouth; those in carious teeth are often sufficient to injuriously affect digestion and health.  The healthy gastric juice is to a great degree antiseptic, but few bacteria being able to endure its acidity.  When the residue of the food reaches the large intestine, bacteria are found in very great numbers.  The warmth of the body is highly favourable to their growth.  They cause the food and intestinal debris to assume its faecal character.  Should the mass be retained, the bacterial poisons accumutate and being absorbed into the body produce headaches, exhaustion, neurasthenia and other complaints.  Proteid matter, the products of its decomposition and nitrogenous matter generally, are especially the food of bacteria; this is shown in the offensiveness of the faeces of the carnivora, notwithstanding their short intestines, compared with that of the herbivora.  Also in