IMMUNITY AND IMMUNIZING AGENTS. 



123 



tion of the precipitate has been termed precipitin. Similar reactions are 

 observed with milk and egg albumen, when used with their specific immune 

 sera. These reactions have been utilized to secure evidence in crimina 

 cases. The serum of an animal which has been injected with human blood 

 (humanized immune serum) produces a precipitate when mixed with 

 human blood, even in high dilutions. Like agglutination, the reaction is, 

 however, not wholly specific. For example, humanized animal serum will 

 also produce a precipitate with the blood of higher apes. Dog immunized 

 animal serum will produce a precipitate with wolf's blood, etc. 



The chief immunizing agents are the bacterolysins, the antitoxins and 

 the leucocytes (phagocytes) aided by the opsonins. The significance of 



Fig. 56. — Illustrating receptors of the third order, or so-called amboceptors. This 

 serves to explain the action of lysins (bacteriolysin, Hemolysin, cell lysins, milk lysins, etc.). 

 The ceE receptor (amboceptor) has two haptophore groups, one (e) capable of uniting 

 with a disintegrated substance as bacterial cell, blood-corpuscle, etc., (/) and the other 

 ig) having the power to combine with a complement (k). h is the haptophore group of 

 the complement (lysin) and z the zymotoxic group. Amboceptors, lysin receptors and 

 receptors of the third order mean the same thing. {Journal of the American Medical 

 Association, 1905, p. 1369.) 



agglutinins and precipitins in the prevention of bacterial disease is not clear. 

 Recent observations on drug action tend to prove that some of these rem- 

 edial agents apparently possess antitoxic and other immunizing properties. 

 It is for example fairly well proven that phosphorus and Echinacea angusii- 

 folia have the power of increasing the opsonic index in certain bacterial in- 

 vasions. Sulphide of carbon and silica appear to check and cure suppurative 

 processes, perhaps due to similar activity. Nuclein which is usually derived 

 from yeast, is reported to be decidedly bactericidal and to increase phago- 

 cytosis to a marked degree. According to Lloyd, Lobelia, when admin- 

 istered hypodermically, counteracts the toxin of the diphtheria bacillus. 



