1 64 POPULAR SCIENCE MONTHLY. 



logical chemistry, true solution of which will do much to explain 

 natural and artificial immunity, the action of toxins and antitoxins, 

 the bactericidal action of blood sera, the effect of oxidizing enzymes of 

 animal and vegetable origin upon toxins of various kinds, etc. Ehr- 

 lich's theories regarding the protection furnished by antitoxic and bac- 

 tericidal serums, so elaborately devised, constitute a working hypothesis 

 of great value, but we need much additional knowledge concerning the 

 nature and action of the so-called complements and anticomplements, 

 of amboceptors, of haptophor groups, of agglutinins, of precipitins and 

 of hemolysis. The physiological chemist studies with care the im- 

 portant and suggestive work being carried forward by the many bril- 

 liant investigators in pathology and bacteriology, with the feeling, 

 however, that the true explanations for most of the phenomena in ques- 

 tion are chemical, and that the actions and interactions involved are 

 chemical ones, to be eventually made clear by a fuller chemical knowl- 

 edge of the toxic and antitoxic substances themselves, and of their 

 alteration and combination under different physiological conditions. 



The well-known natural immunity possessed by some animals 

 toward certain diseases, together with the difficulty experienced by most 

 micro-organisms in developing in the healthy body; a difficulty which 

 at once disappears when from any cause the tissues of the body lose 

 their original vitality and vigor, all point to the presence in the healthy 

 body of certain general or specific substances which are directly dele- 

 terious to the micro-organisms. Such substances are obviously bac- 

 tericidal, and it is equally plain that in the bodies of many species of 

 animals there are specific antisubstances present which are lacking 

 in other species, thereby explaining the natural immunity of the former 

 towards certain diseases. As is well known, blood serum possesses, as a 

 rule, a bactericidal power upon most micro-organisms, and we have 

 every reason to believe in the existence of specific substances in the 

 serum which exert some influence upon the growth and development 

 of micro-organisms, and also upon the toxic products they tend to 

 elaborate. These protective substances — the alexins of Buchner — 

 appear to be proteid in nature, resembling globulins, since they are pre- 

 cipitated from serum by the action of certain strong solutions of alkali 

 salts, as sodium sulphate. We know, however, very little regarding 

 their chemical nature aside from the fact that they are obviously very 

 complex, although perhaps even this point is not quite certain. These 

 protective substances are presumably elaborated by the leucocytes of 

 the blood and lymph, cells rich in nuclein and nucleoproteid material. 

 Doubtless, also, some of the gland cells in the body have a corresponding 

 action ; statements which, if true, tend to emphasize the possible proteid 

 nature of the protective substances. 



While in a general way we may say that the natural immunity to 



