340 



VEHICLES OF CHEMICAL CORRELATION 



in another sample the globulins were removed by half-saturation with 

 ammonium sulphate and the resulting solution of albumins was purified 

 by dialysis and its protein content determined by a nitrogen estimation 

 or by coagulating, and weighing the dried coagulum. These processes 

 were tedious, inaccurate and time-consuming, and the large quantity 

 of blood required necessitated restriction of analyses to single samples 

 or to samples taken at rare intervals from the same animals. 



The recent Refractometric Method of Robertson removes these sources 

 of inaccuracy and permits the determination of the " non-proteins" 

 (including proteoses), globulins, albumins and total proteins in a 

 quantity not exceeding one and one-half cubic centimeters of serum. 

 Samples of this volume may be taken several times in a day from the 

 ear of a rabbit without any evident disturbance due to hemorrhage, 

 and hence the effects of various procedures and administrations may be 

 studied by comparing the composition of the blood-serum of the animals 

 before and at successive intervals after the experimental condition is 

 inaugurated. 



The following are average results obtained by the refractometric 

 method with various species of mammals and birds. 



It must, however, be recollected that the normal proportion of 

 globulin to albumin is subject to considerable fluctuation, not only in 

 different individuals of the same species, but from time to time in the 

 same individual. The following are estimations made by Rowe upon 

 sera derived from eighteen normal persons: 



The last four determinations were made upon samples obtained 

 from the same individual on different dates. It will be observed that 

 the globulins in these normal individuals never exceeded thirty-two 

 per cent, of the total proteins, although ranging from this proportion 

 down to sixteen per cent, in different individuals. On the other hand 

 seventeen persons with Syphilis, and yielding a strongly positive 

 Wassermann Reaction gave values for the proportional globulin content 

 ranging from 26 to 49 per cent., and averaging 35.7 per cent. Eight 



