EXPEKIMENTAL INOCULATION 493 



however, just before death in very severe and rapidly fatal cases. 

 The examination of the blood by means of cultivation experiments 

 is, however, a much more reliable procedure. For this purpose 

 about 5 c.c. of blood may be withdrawn from a vein and dis- 

 tributed in flasks of bouillon (p. 70). It may be said from the 

 results of different investigators that the bacillus may be 

 obtained by culture in fully 50 per cent, of the cases, though 

 the number will necessarily vary in different epidemics. The 

 Advisory Committee, appointed by the Secretary of State for 

 India in 1905, found that in some septicsemic cases the bacilli 

 may be present in the 



blood in large numbers, --aCWfm* . 



two, or even three, days t»* •* I • \ -' 



before death though this ^) ^. ? 'fo^' , 



is exceptional. / f\ * (Jffi >• 



The above types of the °%?l+ • *» tj*?^- 



disease are usually classi- * | /X* ***** > •?/.»«"•$}» 

 tied together under the >*»»%| \* \ «"«»"'••» ***/ 



heading pestis major, but *** /\i"' „/ *** » *In * ,_ * 



there also occur mild i*» ,11 *. r * ♦ •*.-, • ' 



forms to which the term Va * ° **, V ^ •» ,^ * 

 pestis minor is applied. * ^^""i. J •* • V" . I •"" 



4 ' 



In these latter there may * ^ V ' *Vj' *»*•'' i"? «* 



be a moderate degree of ' «• *,*?# ' j^ w i* ' Jr 



swelling of a group of ' * *! ,\ *•**, *"»-' 



glands, attended, with * ... -** -"' 



some pyrexia and general fig. 150.— Film preparation of spleen of rat 



malaise, or there may be af ter inoculation with the bacillus of 



little more than slight pl ??l e < showing > lu ( me . rous baoilli ' lnost of 

 »»~ i"«i" """" o" & "» which are somewhat plump. 



discomfort. Between such Stained with carbol-thionin-blue. x 1000. 



and the graver types, 



cases of all degrees of severity are met with. 



Experimental Inoculation. — Mice, guinea-pigs, rats, and 

 rabbits are susceptible to inoculation, the two former being on 

 the whole most suitable for experimental purposes, After sub- 

 cutaneous injection there occurs a local inflammatory oedema, 

 which is followed by inflammatory swelling of the corresponding 

 lymphatic glands, and thereafter by a general infection. The 

 lesions in the lymphatic glands correspond in their main 

 characters with those in the human subject, although usually 

 at the time of death they have not reached a stage so advanced. 

 By this method of inoculation mice usually die in 1 to 3 days, 

 guinea-pigs and rats in 2 to 5 days, and rabbits in 4 to 7 days. 

 Post mortem the chief changes, in addition to the glandular 



