EXPERIMENTAL,. 23 



These reactions show that changes occur which involve the albumin coag- 

 ulating at 55, for after freeing the extract from all protein precipitable by 

 saturating with sodium chloride or by dialysis there remains in solution only 

 a small proportion of this albumin. 



Thus an aqueous extract corresponding to 666 grams of germ meal, when 

 heated to 65, yielded 62 grams of coagulum, or 9.3 per cent ; a similar ex- 

 tract on dialysis deposited 9.2 per cent ; only 0.87 per cent of coagulable and 

 2.0 per cent of uncoagulable protein remaining in solution. The precipitate, 

 produced by dialysis, was but slightly soluble in sodium chloride solution, 

 having become largely coagulated. From these facts it is clear that one and 

 the same protein substance gives rise to these apparently different protein 

 bodies, and consequently the substance which O'Brien considered to be a 

 globulin of the myosin type and an albumin, coagulating at 80, are in fact 

 derivatives of the albumin, which coagulates mostly at 65. 



These changes are due to a slow development of acid in the extract, which 

 not only brings about hydroly tic changes in the protein, but may also lead to 

 the formation of different compounds between the protein and the various 

 acids contained in the extract, and so give rise to chemically different sub- 

 stances. Such a development of acid takes place rapidly in muscle plasma, 

 under the influence of which quite similar changes in the proteins there 

 present can be observed. 



Why Frankfurt overlooked albumin, present in such large proportion in 

 the aqueous extract, is not easily understood, unless, before heating his solu- 

 tions, he either added no acid or so much that he converted this substance 

 into an uncoagulable acid compound. 



Hydrochloric acid added to the extract in very small quantity causes a 

 flocculent coagulum to separate on heating, while a slightly larger quantity, 

 added before heating, entirely prevents the formation of this coagulum. 

 Acetic acid and nitric acid give precipitates in the extracts which are not 

 soluble in a reasonable excess of either of these acids. 



THE ALBUMIN OF THE WHEAT EMBRYO. 



In order to determine definitely the relations of these variously obtained 

 substances, a large number of fractional precipitations have been made under 

 quite different conditions, an account of which is now given 



An extract was made by treating 700 grams of germ meal with 5 liters of 

 water, straining through bolting-cloth and filtering the fluid perfectly clear. 

 A portion of it was at once heated for i hour in a water-bath at 60, and the 

 large coagulum produced gave 24 grams of preparation 6. 



Another preparation was made by heating in a water-bath at 65 2000 cc. 

 of a clear aqueous extract, obtained by treating 3000 grams of the germ meal 



