In connection with this interesting and important discussion, the following observations by Tsclierwinsky arc referred to in Landois' "Textbook of Human Physiology." He fed two similar pigs from the same litter. 

No. 1 weighed 7,300 grammes ; 

No. 2 7,290 grammes. No. 1 was killed, and its fat and proteids estimated. No. 2 was fed for four months on grain, and then killed. The grain and excreta and the undigested fat and proteins were analysed, so that the amount of fat and proteins absorbed in four months was estimated. The pig then weighed 24 kilos. ; 11 was killed, and its fat and proteins were estimated : — 

No. II. contained 2.50 kilos. of albumen and 9.25 kilos. of fat 

No. I.                        0.94 „                                        „ 0.69 „ 

Assimilated            1.56 „                                        „ 8.56 „ 

Taken in in Food   7-49 „                                      „ 0.66 „

Difference            — 5.93                                      " +7.90"     

There were therefore 7.90 kilos, of fat in the body which could not be accounted for in the fat of the food. The 5.93 kilos. of albumen of the food which were not assimilated as albumen could yield only a small part of the 7.90 kilos, of fat, so that at least 5 kilos. of fat must have been formed from carbohydrates. Lawes and Gilbert calculated that 40 per cent of the fat in pigs was derived from carbohydrates. How the carbohydrates changed into fat in the body is entirely unknown." 

As has already been stated, the weight of evidence appears to be distinctly in favour of the conclusion that, in some way or other, the carbohydrates are capable of being converted into fat in the system ; but, in any case, the same result occurs, and they promote, either directly or indirectly, the deposition of fat within the body. 

The probability that lactic and other acids of the same class are formed in the body, chiefly or solely from carbohydrates, is drawn attention to by Parkes. "The formation of these acids is certainly most important in nutrition, for the various reactions of the fluids, which offer so striking a contrast (the alkalinity of the blood, the acidity of most mucous secretions, of the sweat, urine, etc.), must be chiefly owing to the action, of lactic acid on the phosphates or the chlorides, and to the ease with which it is oxidised and removed." We may conclude, then, that the carbohydrates by their capacity for rapid metabolism contribute largely to the production of heat and mechanical work, find also that their use greatly favours an increase in the constituents of the body, and especially of the albumen and fat. If we desire to increase the albumen without adding greatly to the store of fat, we should (according to Bauer) give a liberal allowance of albuminates with relatively small quantities of carbohydrates. But if we desire a substantial addition to the fat, the food should contain less albumen and more carbohydrates, with a fair proportion of fats.