BEHAVIOR TOWARD POLARIZED LIGHT. 33 



takes place varies in the different representatives of the group, 

 it is possible thus to separate them from each other, and to identify 

 the individual forms. A certain care, however, is necessary in this 

 process, as the temperature of coagulation for any one albumin 

 varies within fairly wide limits according to the concentration and 

 reaction of the solution, and the kind and amount of salts that may 

 at the same time be present. 



Denaturization. It has been pointed out that coagulation alters 

 the character of all albumins in a profound manner, as is evidenced 

 by the fact that they are then no longer soluble in the usual media. 

 Of the changes which take place in the albuminous molecule during 

 this process we know nothing. When once coagulated, however, it 

 is only possible to effect their solution by chemical processes, which 

 are calculated to bring about definite changes in structure. Aside 

 from their digestion with ferments, the coagulated albumins may be 

 dissolved by treating with dilute solutions of the alkalies or mineral 

 acids, or with concentrated organic acids under the influence of heat. 

 They are thus transformed into alkaline albuminates and acid albu- 

 mins, or syntonins. The changes which the albumins thus undergo, 

 Neumeister has termed the denaturization of albumins. As a con- 

 sequence, the products which are thus formed differ not only from 

 the native albumins in their general chemical composition, but also: 

 in their properties. They are thus insoluble in neutral solutions, 

 but dissolve with ease in solutions of the alkaline hydrates, of sodium 

 carbonate, and in hydrochloric acid. From their acid solutions they 

 are precipitated by saturation with sodium chloride or ammonium 

 sulphate. To undergo this change, it is not necessary, however, 

 that the native albumins have been previously coagulated, as solu- 

 tions of the albumins, which have been boiled after the addition 

 of alkalies, or large amounts of organic acids, and have thus 

 been prevented from undergoing coagulation, behave in the same 

 manner. 



Behavior tov/ard Polarized Light. All albumins are leevo- 

 rotatory /. e., they turn the plane of polarized light to the left. 

 As the degree of rotation varies with the different members of the 

 group and the amount of albumin present, it is thus possible, not 

 only to identify the individual bodies, but also to determine the 

 amount present. The specific rotatory power of some of the more 

 important representatives of the group, for the yellow line D, is as 

 follows : 



Ksg-albumin (a) D 33-38 



Serum-albumin 



Lactalbumin 



Serum-globulin 



Fibrinogen 



Syntonin (from myosin) 



Casein (dissolved in magnesium sulphate solution) 



56 



59-75 c 

 43 



72 Q 

 80 



Alkaline albuminate ' 62.2 



Various albumoses u 70-80 



8 



