Of the different classes of food stuffs, there are some which are absorbed readily by the rectum, while others are scarcely taken up at all. To the latter class belong starches and most of the fats. Those starches which are predigested and partially converted into sugar may be absorbed to a very limited extent, but not sufficiently to add to the nutrition of the body. Maltine may sometimes be absorbed. Fats and oils not only remain unabsorbed by the rectum, but they prevent the absorption of other foods by coating either the mucous membrane or the food itself, and are therefore worse than useless. Attempts have been made to give them saponified or finely emulsified, prepared with pancreatin or otherwise, but it is doubtful if even under these circumstances enough of any form of fat or oil can be taken up to be of practical benefit in rectal feeding.

It is exceedingly important to use only materials which will be as completely absorbed as possible. Anything else acts as a foreign body, and in time proves more or less irritating. Moreover, it is found that many albuminous materials which are absorbed from the surface of this portion of the intestine become irritating if given in too concentrated a form, such as pure peptone, and they must be diluted to two or three times their volume with water or some bland fluid. Some forms of albumin are undoubtedly absorbed from the mucous membrane of the rectum without predigestion, such as that expressed from chopped meat or egg albumin, but it is much better to at least partially pancreatinise it.

Pancreatinised Meat

In preparing proteid food for absorption one of the forms of pancreatic extract or pancreatin may be used. Extracts of pancreas are open to the objection that they do not keep very long, and unless perfectly fresh they are apt to prove irritating, and glycerin extracts cannot be used in any quantity on account of the aperient action of the glycerin itself. To overcome these difficulties, Leube suggests using the fresh pancreas, which is to be added in the proportion of one part to three of beef. Both the meat and the pancreatic gland should be scraped or thoroughly minced and rubbed into a paste with a little warm water. Any fat should be carefully removed. The pulp thus obtained is to be injected by means of a suitable syringe with a rather wide nozzle. The digestion, which is begun outside, is continued within the rectum. Leube sometimes adds egg albumen and even fat to the mixture.

Sansom gives the following formula for a meat peptone enema suitable for an infant or young child: Shred raw beef or mutton in bulk about two tablespoonfuls, add an equal bulk of water, and let stand for an hour; then add gradually four tablespoonfuls of milk, heated to boiling. When all is well mixed the temperature of the mixture will be about 1400 F., then add a teaspoonful of Savory & Moore's or Benger's liquor pancreaticus, and a pinch of bicarbonate of soda. Let the whole remain for six hours, and heat to boiling. Strain through muslin and preserve the liquid, which will suffice for several enemas.