THE MUTUAL RELATIONS. 321 



526 grams of sugar remain unaccounted for. Liithje assumes that this 

 means that albumin forms sugar. This assumption of Ltithje corresponds 

 to the fact that the elimination of nitrogen, and likewise that of sugar, 

 increases uniformly when the administration of albumin is increased. 

 The ratio of the sugar (dextrose) eliminated to that of the nitrogen in the 



urine is usually designated by the symbol . 



This ratio is assumed to have a constant value, namely, 2 . 8. 1 E. Pfliiger 

 calls attention to the fact that the value is not as constant as is generally 

 supposed, but that very appreciable deviations may arise. Thus, in some 

 of his experiments, Pfliiger found the value to be less than 1, and in 

 other cases it rose as high as 14.6. Furthermore, it must be remembered 

 that every increase in the amount of albumin administered results in the 

 saving of a corresponding amount of fat and carbohydrate. Every addi- 

 tion of albumin lessens the extent to which carbohydrates are oxidized. 

 Now diabetics, as well as animals afflicted with glucosuria, have not lost all 

 of their ability to consume sugar. Some work is performed in both cases 

 at the expense of energy present in sugar. If now albumin be fed in large 

 amounts, this can be burned up in place of the carbohydrates formerly 

 required. The result of this will be that more unconsumed sugar circu- 

 lates in the blood, and is, therefore, eliminated. This also would account 

 for the parallel elimination of sugar and of nitrogen. 2 



If we consider all that we know with regard to the formation of sugar 

 from substances other than carbohydrates, we arrive at the conclusion that 

 it is at present impossible to decide whether fats or proteins must be drawn 

 upon as a further source of supply. We know merely that sugar can be 

 produced from one of these two classes of compounds. From a chemical 

 standpoint, the transformation of fatty acids into sugar is just as com- 

 plicated as is that from the amino acids; yes, we may say, that the con- 

 version of the oxyamino acids into carbohydrates is easier to understand, 

 because glucosamine may be regarded as a compound intermediate between 

 the two latter groups. On the other hand, we must not forget that a very 

 large part of the albumin molecule is composed of simple amino acids. 



The question as to whether sugar is produced from fats or from albumins 

 is probably an unnecessary one. We can see no particular reason why 

 both should not be utilized in this way, according to the conditions. Such 

 an assumption would explain the observed irregularities, and enable us to 



understand why the quotient should at one time be less than 1, and 



grams serum would not have over 1.5 grams sugar in a free form, 4100 cubic centi- 

 meters must contain less than 6.15 grams. 



1 O. Minkowski: Arch. exp. Path. Pharm. 31, 85 and 97 (1892). 



2 E. Pfliiger: Glycogen, loc. cit. p. 325. Cf. also Lecture I, pp. 6 and 7. 



