THEORIES 01-' IMN! t x ETV. In I Pasteur taught that the micrth;rganisin, by its growth in the body, u-es up some substances necessary for its existence, and then perishes. If the removal of this substance he complete. perfect, immunity results. This is the theory. berg combats it, that if it were true, we must Immure in each of our bodies certain smallpox material, measles material. and scarlet-fever material, etc., each of which must be exhausted by its appropriate micrth;rgminism, thus neces sitating an almost inconeeivnbly complex chemistry. The l nimon theory was advanced in 'Aso by Chativeau. who suggested that the growth of the bacteria in the body probably originated some substanve prejudicial to their further development. The phagorytosis theory was suggested by Carl Roser in ISS11, received attention from Sternberg. and also from Koch, but was not advanced with any insistence till. in 18S4 Metchnikot• enthusiastically championed it and gave it his name. There are two varieties of the White blood-eorptiscle whose duty it is to destroy bacteria: these arc the large. unicellular leucocyte, or inaerophagocyte, and the smaller form. the inicropliagoeyte. Butte these forms exhibit anu•boid movements. and possess the at tractive force railed chemotaxis which exists be tween anarboid cells and fothl particles. Pima gocytosis is the incorporation of foreign particles by these anneboid white blood-corpuselos. Lea cocytes actually take up and envelop living pathogenic organisms, as demonstrated by Koch in 1S78. The humored theory, suggested by :robin:Ann in 1SS4, wits advanced by Buchner, who claimed that not pliagocytosis, lint the bacte ricidal action of blood-plasma. is the cause if the destruction of pathogenic bacteria. lie showed that freshly drained blood. blothl-plasma. as well
as aqueous liumol destroyed such organisms. It was shown in rebuttal that dispersion in a large amount. of watery fluid the death of micro Which grow well when allowed to re main in a close colony. The prevalent and generally adopted theory is the antitoxin theory, defended by Behring, and Kitasato. Brieger, Tizzoni. Cat tani, Roux, Valliant, and others. According to this theory, the metabolism of bacteria. during disease, gives rise in the blood of the sick person, not only to poisonous alkaloids called toxins (ex isting either in the bodies of the bacteria or pro (lured by them). but also to defensive proteids called anti-toxins, which possess the property of neutralizing the toxins. nankin divides the anti toxins (formerly called ati.rins by Ituchner) into four groups. Proteid substances that occur naturally in animals and possess the power of destroying bacteria or their products, he calls sons. Similar proteids resulting from acquired immunity in animals he call- phylaxins. Sozins are subdivided into those which have the property of killing baeteria, or inyeosozins, and those which neutralize bacterial products. or to.ro sozins. A phylaxin which destroys bacteria he calls a in.yrophyla.ria. and a phylaxin which neu tralizes their ptomains he calls a to.roph Oa xi n. Consult: Roser, Entziindung mid I)eilung (Leip zig, 1SP,11); Chauveau, Trait,' de physivic blob). gigue (Paris, 1901) ; Behring. Irie Ma/serum tluruy,ir (Leipzig, 1892); Sternberg, Immunity: Protective: in Infectious Diseases and Nertun 7hcropy (New Nod:, IS95). For the method of securing artificial immunity by means of defensive proteids, Sc(' ANTITOXIN ; TOXINS; SERUM ; and VACCINATION.