the Optical Rotation of the Proteins of Blood Sera. 183 



extinction coefficients of serum must be multiplied by l - 25 or those of the 

 proteins by - 8. 



Each of the protein curves is in general similar in form and character to 

 that of serum (loc. cit.), which demonstrates that the band produced by serum 

 is an expression of its protein-content, especially since serum deprived of its 

 protein gives no such band {loc. cit.). 



It now remains to consider the specimens employed and the curve for each 

 protein in detail. In all, eleven specimens of serum were studied, six derived 

 from the horse and five human. The primary object in employing horse serum 

 was to ascertain the best conditions for separating and purifying the proteins, 

 so that the human serum might afterwards be studied with greater confidence 

 and certainty. The two or three earlier numbers amongst the horse specimens 

 may therefore be regarded as practice numbers, and to that extent the figures 

 for these must be held as less reliable. 



The horse serum was as nearly as possible strictly normal, as the first 

 three specimens were supplied as such from a physiological laboratory ; and 

 the three later specimens were derived from animals slaughtered for use as 

 human food. The serum was mixed with an equal volume of saturated 

 ammonium sulphate solution within 24 hours of the slaughter of the horse. 



The last of the specimens of human serum (No. 205) was declared to be 

 strictly " normal," and was from a case of cerebral ha3morrhage. The other 

 four were selected specimens of ascitic fluid. Each one was quite clear and 

 had the appearance of good serum : No. 200 being the least satisfactory, 

 although that was good. 



The three later specimens of horse serum and those of ascitic fluid were 

 all sufficiently large. That of normal human serum was smaller, namely, 

 250 c.c. ; but in this case, by careful manipulation, satisfactory separation 

 and purification of the three proteins were effected. 



The experimental data are collated in Tables I to VI, in which the specific 

 rotations are repeated for the sake of easy reference. The results are 

 graphically displayed in the accompanying curves, which have been arranged 

 in two groups, namely, the three proteins from horse serum in the one, and 

 those of human origin in the other. This is convenient, because the curves 

 for the two pseudo-globulins are so very nearly alike that they may be 

 regarded as the one a replica of the other. 



The values brought together in the Tables for study and comparison are 

 (a) the extinction coefficient at the head of the absorption band at a wave- 

 length of about 2800 ; (b) the extinction coefficient at the point in the band 

 where the light-absorbing power is least at a wave-length of about 2500, 

 that is, in the depression of the curve ; (c) the difference between («) 



