220 ANNUAL REPOKTS OF DEPARTMENT OF AGRICULTUrwE. 



The examination of tomato-seecl oil has been completed, and the 

 data thus secured submitted for publication. 



A survey of the industrial recovery of wool grease has demon- 

 strated clearly the necessity for a systematic investigation, to the end 

 that less of this valuable material be wasted in the process of scour- 

 ing wool. 



CHEMISTRY AND NUTRITIVE VALUE OF PROTEINS. 



The physico-chemical examination of gelatin has led to the publi- 

 cation of two articles entitled, respectively, "The Mutarotation of 

 Gelatin and Its Significance in Gelation " and " The Effect of Hydro- 

 gen Ion Concentration on the Liquefaction of Gelatin," and to the 

 preparation of a third, entitled "Determination of the Jellying 

 Power of Gelatins and Glues by the Polariscope," which proposes a 

 method for testing gelatins and glues based upon changes in rota- 

 tory power. 



The basic amino acid, lysin, wdiich is believed to be an essential 

 ingredient of diets capable of supporting growth, was disco verd in 

 hordein, the principal protein of barley. 



A summary of the work on the proteins of the peanut and a pre- 

 liminary announcement of the value of peanut flour in wheat bread 

 has been presented. A loaf made from wheat flour with a small ad- 

 mixture of peanut flour and salts furnishes a diet that is biologically 

 complete, is properly utilized by animals, and maintains normal 

 growth. Even smaller amounts of soy-bean meal will give similar 

 results. 



The hydrolysis of stizolobin, the globulin of the Chinese velvet 

 bean, Stizolohium riiveicm, has been completed. Two and one-half 

 per cent of hydrox3^glutaminic acid and from 9 to 10 per cent of as- 

 partic acid were obtained from it. Rats fed upon a diet containing as 

 the sole source of nitrogen the protein of the Georgia velvet bean grew 

 normally to maturity. Further work is necessary to determine why 

 the bean itself does not sustain growth. As has long been known, 

 the globulin of the navy bean will not support normal grow^th. The 

 bureau has discovered that if cystine be added to such a diet this 

 protein will support growth. Moreover, normal growth can be 

 obtained upon a diet containing navy beans to which cystine has been 

 added. It also appears that the nutritive value of the globulin is 

 somewhat improved by heating the protein in water. These obser- 

 vations are so suggestive that similar work upon other species of 

 beans will be begun to determine if they, too, are deficient in cystine. 



The data showing that coconut globulin contains all of the basic 

 amino acids necessary to growth and tliat it, as well as crude coco- 

 nut press cake, is capable of supporting growth, have been pre- 

 sented. ' It was subsequently found that mixtures of certain corn 

 feeds with coconut press cake produce normal growth, which indi- 

 cates that the coconut press cake contains sufficient water-soluble 

 vitamine when the diet consists of equal amounts of the corn feed and 

 the press cake. These findings justify the opinion expressed in the 

 Report of the Chemist for 1918 that it is extremely desirable to 

 retain in this country the copra -crushing industry which developed 

 during the war. 



