THE MUTUAL RELATIONS. 327 



which had been freed as much as possible from fat, could not obtain any 

 definite results. The fat formed may very easily have been derived from 

 the fat of the meat. These experiments also are not suitable to establish 

 the fact that fat is produced from albumin. 



Finally, it may be mentioned that the fat contents of the secretions, 

 those of the lacteal and sebaceous glands, have repeatedly been referred 

 to albumin as their source. Direct experiments do not confirm this 

 assumption. It is also difficult to decide this question, owing to the fact 

 that the animal organism has stores of fat at its disposal, and is not depend- 

 ent on the fat in the food. Moreover, the conversion of carbohydrates 

 into fat must be taken into consideration. 



Now we happen to know of a number of processes in which organs, 

 containing, as far as the eye can see, hardly any fat at all, are suddenly 

 permeated with it. This is especially noticeable in the case of the liver. 

 We have already met with an infiltration of fat in this organ. We have 

 seen, that, as the glycogen disappears after glucosuria has been brought 

 about by phloridzin, fat will take its place, provided, of course, that no 

 carbohydrates are present in the food. We have here a physiological 

 infiltration of fat. It is especially noteworthy owing to the fact that it 

 disappears again on discontinuing the poisoning by phloridzin. Normal 

 liver cells, capable of performing their functions, will remain. 



We know of a large number of poisons, such as phosphorus, arsenic, 

 antimony, chloroform, alcohol, English oil of pennyroyal, etc., all of 

 which are capable of causing a local accumulation of fat. Finally, pathol- 

 ogists are well acquainted with the appearance of a " fatty degeneration," 

 which follows various disease processes (influence of toxins, etc.). We can 

 very easily imagine that the appearance of acute accumulations of fat in 

 places where we would hardly expect to find any, would lead to the con- 

 clusion that some substance had been changed into fat at that place. As 

 the body cells are generally composed of albumin, it seemed to prove that a 

 transformation of albumin into fat had taken place. This conception re- 

 mained for a long time undisputed, until it was shown both macroscopically 

 and microscopically, that this fat could have no connection with the true 

 fat content of an organ. A tissue apparently free from fat may yet contain 

 as much as 20 per cent, and an organ seemingly laden with fat may 

 actually possess less than an apparently fat-free tissue. It was necessary 

 first to trace the formation of fat by exact quantitative methods. A 

 great advance was also made in the discovery that it was not sufficient 

 to determine the fat content of any specific organ, but that the amount 

 of fat in the entire animal must be taken into consideration. We can pass 

 over the earlier experiments in this direction, which were characterized 

 by questionable methods for estimating the fat, and confine ourselves to 

 the more recent work. 



