BY JAMES M. PETRIE. 815 



beans, edestins of cereals and many other seeds, excelsin of the 

 Para-nut, conglutin of lupins, amandin of almonds and peach 

 stones, avenalin of oats, corylin of the walnut. 



In the differentiation of the globulins and albumins our 

 methods have quite recently undergone a fundamental change, 

 -chiefly through the exact experimental work of Osborne on plant- 

 proteins, and Mellanby on animal-proteins. Hitherto we have 

 been guided by the teaching of Hammersten, that complete 

 saturation with magnesium sulphate precipitated globulins only, 

 and of Hofmeister that the same result was obtained by half- 

 saturation with ammonium sulphate, and these statements were 

 comprehended in the definitions. Osborne and Harris(42) have 

 now proved the utter impossibility of separating vegetable 

 globulins from albumins by means of their ammonium sulphate 

 precipitation-limits; in the curves there exist no definite breaks 

 such as are necessary for the assumption that different proteins 

 are precipitated by certain concentrations of salt. Mellanby(43) 

 obtained 47 % of serum-protein by complete saturation with 

 magnesium sulphate and 71 % by half-saturation with ammonium 

 sulphate, and these were assumed by the old definitions to be 

 interchangeable as globulin-precipitants. There is in fact only 

 3 % of globulin in serum-proteins. The same author has succeeded 

 in obtaining a correct differentiation of the serum-proteins into 

 a globulin and two albumins by fractional precipitation with 

 various strengths of alcohol. 



Albumins are distinguished from globulins by the complete 

 absence of the glycocoll-nucleus. They are soluble in pure water, 

 while the globulins are quite insoluble. In treating seeds with 

 distilled water globulins also go into solution by the presence of 

 soluble inorganic salts in the seeds; we are therefore really 

 extracting with a dilute salt solution. The separation is made 

 by dialysis, when, on complete removal of all salts, the globulins 

 are rendered insoluble. 



3. The group of alcohol-soluble proteins includes the gliadin 

 of wheat, zein of maize, and hordein of barley. They contain no 

 glycocoll or lysin nucleus in their constitution, but are rich in 



