THE PNEUMOCOCCUS AND PNEUMONIA 457 



subject of the inoculation. Subcutaneous inoculation of virulent 

 pneumococci into mice and rabbits usually results in an edematous 

 exudation at the point of inoculation, which leads to septicemia and 

 death within twenty-four to seventy-two or more hours. When the 

 dose has been extremely small or the culture unusually attenuated, 

 a localized abscess may be the only result. Intravenous inoculation 

 is usually more rapidly fatal in these animals than the subcutaneous 

 method. Intraperitoneal inoculation in rabbits results in the forma- 

 tion of a rapidly spreading peritonitis in which the exudates are apt 

 to be accompanied by a deposit of fibrin, and to lack the transparent 

 red color so often caused by the hemolyzing streptococci. With 

 very virulent strains, these differences are less marked. In almost 

 all of these infections death is preceded by septicemia and the micro- 

 organisms can be recovered from the heart's blood of the victims. 



The production in animals of lesions comparable to the lobar 

 pneumonia of human subjects has long been the aim of many in- 

 vestigators. Wadsworth, 62 recognizing that such lesions probably 

 depended upon the partial immunity which enabled the infected 

 subjects to localize the pneumococcus processes in the lungs after 

 infection by way of the respiratory passages, succeeded in producing 

 typical lobar pneumonia in rabbits by partially immunizing these 

 animals and inoculating them intratracheally with pneumococci of 

 varying virulence. Lamar and Meltzer 63 produced lobar pneumonia 

 in dogs in 1912 by injecting cultures in the bronchi and blowing 

 them into the finer bronchioles with air. Similar experiments have 

 been made by Winternitz and Hirschfelder. 64 



The most striking parallelism between experimental animal in- 

 fection and pneumonia as it occurs in man has recently been obtained 

 by Cecil and Blake. Using Macaccus and other species of monkey, 

 they injected small amounts, 0.1 to 0.2 c.c. of virulent pneumococcus 

 cultures directly into the trachea of these animals, and, after an 

 incubation time of a day or slightly longer, they obtained typical 

 lobar pneumonias. This work will be further spoken of below. 



62 Wadsworth, Amer. Jour. Med. Sci., May, 1904. 



63 Lamar and Meltser, Jour. Exp. Med., xv, 1912. 



94 Winternitz and Hirschfelder, Jour. Exp. Med., xvii, 1913. 



