39 



disposed to regard as uncertain any researches in which 

 these measures most essential to accuracy of observation 

 are neglected. Having demonstrated the life history of 

 the bacillus anthracis, which the French school, working 

 with Pasteur's clumsy method, had for sixteen years failed 

 to discover, Koch turned his attention to the etiology of 

 surgical infectious diseases. He found that the subcu- 

 taneous injection into a mouse of five drops of putrid 

 blood was followed by immediate prostration, and in four 

 to eight hours by the death of the animal. Th&re oc- 

 curred in these cases no local reaction, the internal or- 

 gans were apparently normal, no bacteria were detected in 

 the blood or tissues, inoculation of other animals with the 

 blood from the heart caused no perceptible effect. Koch 

 considers this disease therefore as septicaemia, etymo- 

 logically as well as clinically the introduction into the 

 blood of a poisonous substance, soluble, not reprodu- 

 cing itself, analogous, in fact, with the effect of certain 

 vegetable alkaloids and of ptomain, the substance iso- 

 lated by Selmi from human corpses, which so closely re- 

 sembles atropine in its physiological effects. This is 

 also the effect obtained from the injection of boiled pu- 

 trid materials by Panum, Bergmann and Schmiedeberg, 

 and others. Koch found, however, that the injection of 

 a smaller quantity, one-half to one drop of the same pu- 

 trid blood, was followed by entirely different effects. In 

 some cases the mouse was apparently unaffected ; in 

 others brief, transient depression was observed ; in per- 

 haps one-third of the cases there ensued, twenty-four 

 hours later, progressive weakness, retardation of respira- 

 tion, drowsiness, and, in forty to sixty hours, death. Sec- 

 tion revealed no other pathological changes than local 

 redema at site of inoculation and decided enlargement 

 of the spleen ; but after inoculation of a second mouse 

 with a minute quantity (one-tenth to one-half drop) of 

 liquid from this oedema, or of blood from the heart, the 

 latter animal presented, in forty to sixty hours, precisely 

 the same clinical and pathological picture as the first ; 

 from the second, a third was successfully inoculated, and 



