LOCALISATION OF INFECTION 177 



average of only 5 per cent, of lesions in the appendix in 

 animals injected with strains isolated from sources other 

 than appendicitis. Eighteen strains from ulcer of the 

 stomach or duodenum produced haemorrhages in 60 per 

 cent., and ulcer of the stomach or duodenum in 60 per 

 cent., in contrast to an average of 20 per cent, haemor- 

 rhages and 9 per cent, ulcer following injection of other 

 strains. Twelve strains from cholecystitis produced 

 lesions in the gall-bladder in 80 per cent, of forty-one 

 animals injected, in contrast to an average incidence of 

 lesions here of only 11 per cent, with other strains. 

 Twenty-four strains from rheumatic fever produced 

 arthritis in 66 per cent., endocarditis in 46 per cent., 

 pericarditis in 27 per cent., and myocarditis in 44 per 

 cent, of seventy-one animals injected, in contrast to an 

 average of arthritis in 27 per cent., endocardial lesions in 

 14 per cent., pericarditis in 2 per cent., and myocarditis 

 in 10 per cent, of animals injected with strains from 

 sources other than rheumatic fever. Six strains from 

 erythema nodosum produced lesions of the skin in 90 

 per cent, of twenty animals injected, in contrast to an 

 average of 2 per cent, in animals injected with strains from 

 sources other than erythema nodosum and herpes zoster. 

 Eleven strains from herpes zoster produced herpetiform 

 lesions of the skin, lip, tongue, or conjunctiva in 77 per 

 cent, of sixty-one animals injected, in contrast to an 

 average of only 1 per cent, of what seemed to be herpes 

 of the skin with other strains. 



Infection, if not too rapidly fatal, is frequently followed 

 by remarkable alterations in the body fluids and tissues. 

 One of these, if recovery ensues, is the production of im- 

 munity or insusceptibility to the same infecting agent ; 

 this will be considered later (p. 239). Another is the 

 formation in quantity of substances which normally are 

 absent or are present only in small amount, such as 



M.B. 12 



