Highlights in the History of Microbiology 39 



animals to the blood of healthv animals and could cause the same 

 disease. Pasteur reported similar findings with respect to silk 

 worm disease caused bv protozoan parasites. Robert Koch con- 

 firmed the findings of Davaine and expanded materially on the 

 subject as we shall see later in the chapter. 



Because Koch is considered high on the list of famous micro- 

 biologists, second probably only to Pasteur, his accomplishments 

 deserve more detailed evaluation than many other workers men- 

 tioned in this chapter on the highlights of microbiology. He was 

 a rural practitioner in Wollstein, Germany, and at the time that 

 news of Pasteur's work reached him, he was employed at an in- 

 sane asvlum in Hamburg. The potential possibilities in this new 

 biological field intrigued him, and his tendency to let his medical 

 practice fall by the wayside became more pronounced with the 

 passage of time. His first microscope was a present from his 

 wife on his twenty-eighth birthday. 



In this dvnamic period during the latter half of the nineteenth 

 century, Koch became increasingly alarmed at the tremendous 

 economic loss being incurred as the result of anthrax infection in 

 domestic animals. Those who could least afford to lose their 

 animals— in some cases the family's sole support— seemed to be 

 taking the brunt of this unconquerable disease. Perfectly healthy- 

 looking sheep would die during the relatively short space of a 

 single night, and postmortem examination would reveal the tell- 

 tale black blood so characteristic of anthrax. The farmer, or 

 members of his family, might contract horrible-looking boils, and in 

 some instances they would contract the pneumonic type of the 

 disease from breathing in the infectious agent, with painful death 

 culminating their losing battle with respiration. 



Koch laboriously examined untold numbers of blood specimens 

 drawn from healthy sheep and he compared these samples with 

 the blackened blood of the stift^ carcasses of the infected animals. 

 Without exception he found that the blackened blood contained 

 rod-like sticks among the remaining undissolved blood-cells, but 

 these rods were never found in blood from healthy sheep. Since 

 those rods exhibited no locomotion, Koch was hesitant about calling 



