Il6 PHARMACEUTICAL BACTERIOLOGY. 



In 1890 Behring and Kitasato found that the cell-free blood (serum) of 

 rabbits and of mice which had been artificially immunized against tetanii's, 

 neutralized or destroyed the toxic substances of the tetanus bacillus. To 

 this substance they gave the name antitoxin. This was an epoch-making 

 discovery. It led to the finding of other antitoxins or antibodies which are 

 now used in the treatment of disease as will be more fully explained in a sub- 

 sequent chapter. Antitoxins, like the toxins, possess many of the characters 

 of albuminoids, are quite readily decomposed and are incapable of isolation 

 from the blood or from the tissue cells. Never having been obtained in 

 purity nothing is known regarding their physical appearance. They are 

 readily destroyed at comparatively low temperatures (65° to 75° C.) and by 

 exposure to light and air. They are very sensitive to acids and are best pre- 

 served by evaporating the blood sera in which they are contained to dryness 

 in a vacuum at a low temperature and storing in a vacuum, at a low tempera- 

 ture, away from light and in a dry place. Experimentally it has been dem- 

 onstrated that the antitoxins are intimately combined with the globulins 

 of the blood. This discovery led to the manufacture of concentrated anti- 

 toxins by precipitating the globulins with ammonium sulphate, magnesium 

 sulphate and other salts. Remarkably enough, reactions have been ob- 

 served which would indicate that antitoxin is not a proteid substance; for 

 example, it is not destroyed (digested) by trypsin. 



It has furthermore been found that variably small amounts of antitoxins 

 exist in normal blood; that is, in the blood of animals that have not been 

 naturally or artificially immunized, and also in still lesser amounts in the milk 

 of normal animals. As to the origin of the antitoxins the physiologic evi- 

 dence points to their formation in the body cells rather than in the blood 

 serum. 



Another important discovery was that normal blood could actively de- 

 stroy (lake) bacteria, and in common with antitoxins this bactericidal prop- 

 erty was found to be specific. That is, serum found to be quite destructive 

 to the typhoid bacillus is not destructive to the cholera bacillus. These 

 germ destroying or bactericidal substances are designated lysins. Ehrlich 

 has discovered that there are in fact three distinct blood lysins; namely, 

 cytolysin, a substance which is capable of destroying (laking) body cells; 

 hemolysin, which is capable of destroying red blood-corpuscles; and bactero- 

 lysin as already explained. By injecting tissue cells, as those of kidney or 

 of some other organ, into an animal, there are developed in the blood of the 

 inoculated animal lysins which will dissolve kidney cells or other organ cells 

 used. If the blood of a bird or other animal is injected into an animal of a 

 different species, hemolysins will appear in the blood of the animal thus 

 injected. This hemolysin is specific, as it will only dissolve or destroy the 

 hemoglobin in the blood of the kind of animal of which the blood was used 



