SYSTEMATIC AND DESCRIPTIVE. 173 



present in large numbers. If, on the other hand, 

 the animal is not examined until some time after 

 death, then the bacilli are found in the blood of the 

 heart, and distributed all over the body. 



Bacillus of septicaemia of mice, Koch. 

 Extremely minute bacilli, *8 i ft long-, and 'i '2 

 broad, often in pairs, seldom in chains of four. On 

 cultivation they do not appear to make threads, 

 but the bacilli lie together in masses. Spores 

 have been observed. The bacilli are probably non- 

 motile. They are most commonly in the interior 

 of white blood corpuscles. In these they increase, 

 and in many cases a white cell is only represented 

 by a mass of bacilli. The bacilli, or rather their 

 spores, occur in putrid liquids. If a number of 

 mice are inoculated with a minimum quantity of 

 putrid fluid, about a third of them die of septi- 

 caemia, They rapidly sicken, their eyes inflame, 

 their eyelids stick together, they become soporific, 

 and die in from about forty to sixty hours. At the 

 autopsy one finds slight oedema at the seat of inocu- 

 lation, and enlargement of the spleen ; the bacilli 

 are found both free and lodged in the white cor- 

 puscles, in the cedematous tissue, and in the blood 

 capillaries. A minimal quantity of this blood 

 produces the disease if inoculated in house-mice 

 or sparrows. Field-mice have an immunity. Rab- 

 bits and guinea-pigs inoculated in the ear suffer 

 from only a local erythema, which disappears after 

 five or six days, and renders them for a time im- 



