PHENOMENA FOLLOWING IMMUNIZATION 103 



apparent local immunity which occurs in certain infections of the 

 skin. Thus it frequently happens that successive crops of boils may 

 afflict different parts of a patient's skin new ones arising as old 

 ones heal, showing that the process of the limitation and healing of 

 the infected foci is not due to any increase of generalized resistance, 

 but rather to local causes. In the same way, in erysipelas, the process 

 extends along the edges while the original central area of infection 

 is returning to the normal state, and it rarely occurs in adults that 

 the erysipelatous process extends back into the originally infected 

 area. 87 From these localized laboratories of antibody formation, of 

 course, distribution to the circulation probably takes place and the 

 complete cure of the patient must await a sufficient concentration of 

 these in the body as a whole before further local foci cease to arise. 



That the fixed tissue cells of any part of the body can and do 

 take an active part in the local reaction against the invasion of bac- 

 teria and other foreign materials is histologically evident. When 

 a more or less insoluble foreign body a thread of lint, paraffin, 

 agar-agar, or other material is deposited in the subcutaneous tissues 

 anywhere in the body, and is accompanied by acute infection with 

 bacteria, there is a characteristic tissue reaction which results in the 

 surrounding of the foreign particle by multinucleated cells spoken 

 of as giant cells. In the case of foreign bodies such as those men- 

 tioned the process is purely one of local ingestion of the particle 

 which later, if the material remains absolutely insoluble, results in 

 encapsulation by connective tissue. If soluble, however, there may 

 be an eventual digestion of the foreign material by the cell with a 

 subsequent degeneration or splitting up of the giant cell and a return 

 to normal. This also occurs in the case of such infections as those 

 due to yeasts or blastomyces, in which, as the writer has seen, the 

 apparent lack of liberation of toxic products gives rise to a purely 

 local giant-cell reaction, adjacent tissue cells remaining undegener- 

 ated and apparently unaffected. In the case of infection with bac- 

 teria like the bacillus of tuberculosis, the leprosy bacillus, that of 

 rhinoscleroma, and a few others the purely local picture of giant- 

 cell phagocytosis is complicated by secondary reactions arising prob- 

 ably from the liberation of toxic products from the living or dead 

 invaders which both stimulate specific cell reactions and call forth 

 cell degeneration in adjacent tissues, frequently giving the individual 

 infection a diagnostically characteristic appearance. 



87 In children erysipelas not infrequently returns within a few days over a 

 recently healed area. 



