EXCHANGE OF MATERIAL. 451 



stances, a very suggestive disturbance of the functions of the organs, 

 especially the muscles and the nervous system, and death resulted 

 after a time, indeed earlier than in complete starvation. In opposi- 

 tion to these observations BUNGE has suggested that the early death 

 in these cases was not caused by the lack of mineral salts, but more 

 likely by the lack of bases necessary to neutralize the sulphuric 

 acid formed in the burning of the proteids in the organism, which 

 must be then taken from the tissues. In accordance with this view, 

 BUXGE and LUNIN" also found on experimenting on mice that ani- 

 mals which received nearly ash-free food with the addition of 

 sodium carbonate were kept alive twice as long as animals which 

 had the same food without the addition of sodium carbonate. Spe- 

 cial experiments also show that the carbonate cannot be replaced 

 by an equivalent amount of sodium chloride, and that to all appear- 

 ances it acts by combining with the acids formed in the body. The 

 addition of alkali carbonate to the otherwise nearly ash-free food 

 may indeed delay death, but cannot prevent it, and even in the 

 presence of the necessary amount of bases death results for lack of 

 mineral substances in the food. 



In the above series of experiments made by BUNGE the food of 

 the animal consisted of casein, milk-fat, and cane-sugar. While 

 milk alone was an adequate and sufficient food for the animal, 

 BUNGE found that the animal could not be kept alive longer by 

 food consisting of the above constituents of milt and cane-sugar, 

 with the addition of all the mineral substances of milk, than with 

 the food mentioned in the above experiments with the addition of 

 alkali carbonate. The question whether this result is to be ex- 

 plained by the fact that the mineral bodies of milk are chemically 

 combined with the organic constituents of the same and can be 

 assimilated only in such combinations, or whether it depends on 

 other conditions, BUNGE leaves undecided. These observations, 

 however, show how difficult it is to draw positive conclusions from 

 experiments made thus far with food poor in salts. Further investi- 

 gations on this subject seem to be necessary. 



With an insufficient supply of chlorides with the food the elimi- 

 nation of chlorine by the urine decreases constantly, and at last it 

 may stop entirely while the tissues still persistenly retain the chlo- 

 rides. These last are, at least in part, combined in the body with 



