NUTRITION. 



379 



different individuals. Where animals are given food ad libitum it is 

 essential to obtain the data in a statistical manner from large numbers 

 of experiments. The varying total of ingested calories is likewise a 

 factor which must be taken into consideration. 



Despite these unquestioned shortcomings the statistics which we 

 have already gathered confirm our previously expressed views regard- 

 ing the unlike nutritive value of some of the albuminous foodstuffs. 

 In order to bring out this feature more sharply it is obviously desirable 

 to ascertain the protein minima for both growth and maintenance and 

 to institute comparisons on this basis. We have thus found that quan- 

 tities of lactalbumin smaller than those of any other protein tested 

 suffice to meet the requirements of maintenance as well as for growth. 

 A resume of the range of protein minima for maintenance found in 

 the individual experiments is given in the following table: 



Range of protein minima for maintenance in inditfidual expenments. 



Ranges of 7 to 15 milligrams of lactalbumin per gram of rat per 

 week represent minima lower than those found for casein, edestin, 

 milk proteins, or ghadin, not to mention the impossibiUty of mainte- 

 nance with zein. With the pronounced individual variations in the 

 total calorie intake it is impossible to make exact comparisons of rats 

 of the same size on precisely the same intake of protein. It is an 



