904 METABOLISM. 



can be kept alive for any length of time by food entirely free from fat 

 and carbohydrates. 1 But it has been positively demonstrated that they 

 can be kept alive a long time by feeding exclusively with meat freed as 

 much as possible from visible fat (PFLUGER 2 ). Human beings and 

 herbivora, on the contrary, cannot live for any length of time on such 

 food. On the one hand they lose the property of digesting and assimilating 

 the necessarily large amounts of meat, and on the other a distaste for 

 large quantities of meat or proteins soon appears. The elimination of 

 acetone bodies with an exclusion of carbohydrates from the food of man 

 is of interest (see Chapter XIV). 



A question of greater importance is whether it is possible to maintain 

 life in an animal for any length of time with a mixture of simple organic 

 and inorganic foodstuffs. The earlier experiments carried out by many 

 investigators to decide this question have not yielded satisfactory results. 

 and ROHMANN 3 was first able, by feeding a mixture of several proteins 

 with fat, starch, glucose and salts, to keep mice alive for a long time, and 

 was also able to raise young mice by artificial feeding of the mother and 

 then the small animals. ROHMANN concludes from his experiments 

 that for the continuous maintenance or for development of the animal 

 a mixture of different proteins is necessary, but more recently he 4 has 

 found that this can be accomplished by a single protein, and the results 

 of his experiment coincide well in this regard with the investigations of 

 OSBORNE and MENDEL (and E. FERRY S ). 



In experiments with white mice these investigators have found that 

 on feeding with a mixture of only one protein with cane-sugar, starch, 

 fat, agar-agar and mineral substances, adult mice could be kept for 169- 

 259 days without changing their body weight. The reason why the 

 adult mice could not be maintained for a still longer time and why young 

 mice did not grow was that certain substances of unknown kind were 

 lacking. Such substances occur in milk, and by adding to the food, milk 

 from which the proteins have been removed, although the food contained 

 only one protein, the animals can be kept alive for a longer time 500-600 

 days, and the normal growth accomplished as well. These proteins were, 

 especially, casein, lactalbumin, ovalbumin, hemp-seed edestin, wheat 

 giutenin and excelsin, while on the contrary they were not able to pro- 



1 See Horbaczewski, Maly's Jahresber., 31, 715. 



2 Pfluger's Arch., 50. 



3 F. Rohmann, Klin, therap. Wochenschr., No. 40, 1902, and Allg. med. Centralbl. 

 Zeitung, 1908, No. 9. 



4 Rohmann, Bioch. Zeitschr., 39. 



6 Th. B. Osborne and L. B. Mendell, Science, 34. The Carnegie Institution, Wash- 

 ington, Parts 1 and 2, 1911; with Edna Ferry, Journ. of biol. Chem., 12 and 13, and 

 Zeitschr. f. physiol. Chem., 80. 



