AKTIFICIAL METHODS OF FEEDING 811 



was little, if any, higher than that seen in the urine of fasting men or of 

 patients who received only saline by rectum. 2. Modern physiological 

 opinion holds that proteins are absorbed principally as amino-acids, and 

 the failure of the rectum to absorb ordinary nutrient enemata is largely 

 due to the fact that peptones are usually given instead of amino-acids. 3. 

 Chemically prepared amino-acids or milk pancreatized for twenty-four 

 hours, so that the amino-acids are separated, allows a much better absorp- 

 tion of nitrogen as shown by the high nitrogen output in the urine. 4. The 

 low output of ammonia nitrogen shows that the high total nitrogen was 

 not due to the absorption of putrefactive bodies when the amino-acids 

 were used. 



Bauer showed that peptones, meat juices and alkali albuminates were 

 absorbed by rectum but only when salt was added, also that propeptones, 

 milk, casein, globulins and egg albumin salted or mixed with pepsin were 

 absorbed. 



From the foregoing, it is seen that some confusion still exists as to 

 just how well the various forms of protein are absorbed, but in general it 

 may be said that "the nearer the protein molecule approaches its ultimate 

 fate in normal digestion, i. e., as amino-acids, the better is its absorption." 

 So we find peptone better absorbed than albumin, amino-acids than pep- 

 tone, the best rate of absorption being seen when salt is added to the enema. 

 Amino-acids may be most conveniently produced by the pancreatization 

 of milk for 24 hours, in which condition a fair amount is absorbed but not 

 enough to prevent a constant negative nitrogen balance. There are also 

 amino-acids produced chemically from beef, but they are not so well borne, 

 causing rectal irritation. 



Fats. The role of fats in rectal feeding is a very minor one, and 

 authorities differ again as to this. Friedenwald and Riirah believe that 

 fat in fine emulsion, as in egg yoke, is fairly well absorbed. Short and 

 Bywaters conclude that very little, if any, fat is absorbed, which agrees 

 with Brown's (g) observation that fats given by mouth increase fats in the 

 urine, while if given by rectum they do not. There is no objection to 

 using a finely emulsified fat in the nutrient enema, but there is little 

 object in doing so, as dextrose is well absorbed and takes the place of 

 fats in sparing protein. 



Carbohydrates. These, so to speak, form the sheet anchor in rectal 

 feeding and experimental evidence is definite that they are absorbed fairly 

 readily when offered in proper form and concentration. This has been 

 proven, as in giving dextrose the respiratory quotient was raised and 

 acidosis diminished. Even raw starch has been used and not found in the 

 feces, but dextrinized or malted starch is less irritating than the sugars, 

 according to some authorities, and may be used in their stead. Lactose 

 is poorly absorbed, as shown by the rapid rise of ammonia nitrogen in 

 the urine when this was substituted for dextrose, although it is of some 



