368 EXPERIMENT STATION RECORD. 



'• Polished rice does not exert a toxic effect on animals even when it con- 

 stitutes as much as 80 to 90 per cent of the food mixture. Simple mixtures 

 of rice and egg, rice and milk powder, rice and wheat embryo, carrying such 

 a content of rice, have proved perfectly satisfactory for growth and for pro- 

 longed well-being. 



" The addition of quantities of wheat embryo or of milk powder as small as 

 2 per cent of the food mixture, consisting aside from these constituents of 

 polished rice, casein, salt, and milk fat, furnishes enough of an essential 

 accessory to induce growth. 



" The essential accessory substance, aside from that carried by milk fat, is 

 present in water and in alcoliolic extracts of wheat embryo and of egg yolk. 

 The accessory substance which is soluble in water and in alcohol is stable 

 to heat. Prolonged boiling does not injure it to a noticeable degree. 



"The amounts of water extract (freed from protein by coagulation) which 

 we have found necessary to supply enough of the water-soluble accessory to 

 induce normal growth carry nitrogen equivalent to about 1 per cent of the 

 total nitrogen of the ration. Amounts of alcoholic extract of wheat embryo 

 carrying as litttle as 0.6 gm. of .solids and 0.0095 gm. nitrogen (0.33 per cent 

 of the total nitrogen of the ration) suffice to induce normal growth. 



" The water-soluble accessory is not the same one as is furnished by milk 

 fat. Twenty per cent of milk fat addition does not induce any growth unle.ss 

 the other accessory is supplied. 



" Polished rice and salts, together with sufficient wheat embryo to supply 

 liberal protein and water-soluble accessory additions, do not support growth. 

 The fat-soluble accessory must likewise be supplied before growth can proceed." 



The essential factors in the diet during' growth, E. V. McCollum and 

 Margukrite Davis {Jour. Biol. Cbcm.. 23 (1915), No 1, pp. 231-21,6. figs. 12).— 

 Feeding experiments with laboratory animals (rats) are de.-icribed which are 

 in continuation of the work mentioned above. The basal ration contained 

 casein, from which all the water soluble constituents had been removed by 

 dialysis, dextrin, a mixture of inorganic salts, and agar-agar. In some of the 

 tests these substances alone in varying proportions made up the ration; in 

 other experiments different amounts of butter fat were added; in others, the 

 water and alcohol soluble extract of the wheat embryo; and finally both butter 

 and water-soluble extract were incorporated in the diet. 



From the results obtained the authors conclude that "certain at present un- 

 identified substances aside from protein, carbohydrates, fats, and salts are in- 

 dispensable for growth or prolonged maintenance, nnd furthei'more there is a 

 class of such accessories soluble in fats and another soluble in water and 

 alcohol. From the data available ... it .seems highly probable that, while the 

 amount of accessory substances of either of these clas.ses which is required to 

 induce growth is small, the evidence points to the belief that a certaiu quantity 

 must be present before any growth can take place, and that above this amouut 

 growth seems to be in some measure proportional to the amount of accessories 

 present. 



"It is obvious that in the study of the relative values of isolated proteins 

 fed with mixtures of purified food substances comparable amounts of these two 

 classes of accessories must be supplied. Otherwise no safe interpretation can 

 be put upon the results." 



The cause of the loss of nutritive efficiency of heated milk, E. V. Mc- 

 CoLLVM and Marguerite Davis {Jour. Biol. Chew.. 23 {IDJi}). \o. 1, pp. 2^7- 

 254< fl9»- 6). — In order to ascertain the factors involved in the loss of efficiency 

 of milk by heating (which had been observed in the above experiments), ad- 

 ditional feeding experiments with rats were conducted in which a basal ration 



