TOXINS AND ANTITOXINS 



43 



pseudo-globulin, which constitutes about 78 per cent, of the serum 



protein. This fact is taken advantage of in the so-called concentra- 



tion of antitoxin, in which the pseudo-globulin is thrown down by 



the addition of ammonium sulphate. Heinemann states that pseudo- 



globulins may be broken into fractions, one of which contains the 



antitoxin in highly concentrated 



form, thus making the bulk even 



smaller than by the use of pseudo- 



globulin. The precipitate is col- 



lected, dialyzed free of salt, and 



taken up in water, the final volume 



being considerably less than the 



original amount of serum, there- 



fore containing a greater number 



of antitoxic units per c.c. than the 



whole serum. This does not mean 



that the antitoxin is necessarily a 



globulin, for it resists trypsin diges- 



tion in greater degree than does 



globulin. It is, however, an elec- 



tro-positive colloid. Antitoxin is 



not thrown down in indifferent 



precipitates, and in this respect dif- 



fers from the enzymes, nor does it 



operate in the same quantitative re- 



lations as enzymes. The large size 



of the antitoxin molecule is indi- 



cated by the famous Martin and 



Cherry experiment, which showed 



that if toxin and antitoxin are 



mixed and passed through gelatin 



filters the toxin appears first. The FIG. I. Apparatus for filtration through porce- 



nninr wa<5 hrniifrVit nut hv lam f sm ^ u quantities of material. Between the 



Was fOUgnt OUt Dy rubber tube and the suction apparatus must be 



t-i/-l TVT o A c. e* n -wrVir> inserted a small trap to prevent entrance into the 



nd MadS en, wno fl ask of water when suction is released. The trap 



showed that toxin diffuses ten times is a 8alt ^ utlet tube 



more rapidly than antitoxin. Anti- 



toxin is injured by moist heat of 60 to 70 C, destroyed by moist heat 



of 100 C., and by dry heat of 140 C. 



The influence of temperature on antitoxin is of the utmost prac- 

 tical importance in regard to its preservation for therapeusis. 

 Anderson has estimated the yearly deterioration at different tem- 

 peratures as follows : 



Temperature 

 26-35 C. 



15 C. 



5C. 



Yearly deterioration 

 20 per cent. 

 10 per cent. 

 6 per cent. 



