DIPHTHERIA TOXINE. 101 



by the other reagents for globulins, especially anatrionium and 

 magnesium sulphates. The antitoxine combined exclusively 

 with the latter class, and thus remained in th, filtrate tl &nng 

 the precipitation by dialysis, carbon dioxide;-cV ' ! his- explain*; 

 the contradictory results in the work of BELFANTI and CAKBONE 

 and of DIEUDONNE. 



SENG proceeded as follows in the isolation of his "soluble 

 globulins " : 



The albumins (which do not combine with any antitoxine) are first 

 separated by means of a 5 per cent, solution of alum. The filtrate is 

 dialysed, and this causes the precipitation of slight quantities of the 

 insoluble globulins, which are also free from antitoxine and amount to 

 TT to -% of the total quantity of globulins present. This precipitate is 

 collected and washed with water, and the filtrate ought not to become 

 turbid on the dilution with a large volume of water, or give any reaction 

 for sulphuric acid. The globulin is then precipitated by magnesium sul- 

 phate at 30 C., or by semi-saturation with ammonium sulphate, and the 

 precipitate redissolved and subjected to further treatment by the usual 

 methods (vide supra). It contains somewhat more ash, notably aluminium 

 salts, than the globulins precipitated directly from the serum by means of 

 ammonium sulphate. 



The quantity of these soluble globulins, as compared with those 

 of the normal serum, appears to have been somewhat increased 

 at the cost of the insoluble globulins, but this cannot be demon- 

 strated with certainty. 



SENG has also studied the very important question whether chemical 

 differences can be observed between the soluble globulins of the therapeutic 

 serum, as thus obtained, and those of normal serum separated in the same 

 way. As was to be expected, he has not succeeded in coming to a definite 

 conclusion, but it appears as though at least two important constants 

 viz. , the specific rotation and the temperature of coagulation are higher in 

 the case of the antitoxine globulin than in that of normal globulin. SENG 

 himself remarks, very justifiably, that the physiological bearing of all these 

 factors is far too great to allow of distinct differences being observed be- 

 tween the sera of different animals ; it would be necessary to examine the 

 serum of one animal before, during, and after immunisation. Some definite 

 result might then possibly be obtained. 



Meanwhile this question has received further thorough inves- 

 tigation in a series of researches carried out by Hofmeister's 

 pupils. 



It was found that three distinct kinds of globulins could be 

 separated from the blood serum by fractional precipitation with 

 ammonium sulphate. In the first place, jibrinoglobulin is precipi- 

 tated when the saturation with ammonium sulphate reached 21-5 

 per cent, by volume ; then, according to FULD and SpiRO, 1 Hof- 



1 Fuld and Spiro, " Ueb. labende u. labhemmende Wirkung d. Blutes," 

 Z.f. phys. Ch., xxxi., 132, 1900. 



