BY DR. OSCAR KATZ. 551 



able, as it seemed, whitish points of growth, or colonies, the number 

 of which, however, could without difficulty be calculated by counting 

 the number of colonies at, usually, ten different spots each of the 

 area of one-sixteenth of a square cm. area, cut out of a piece of black 

 paper. The total number of colonies which were calculated as being 

 contained in the four tubes, amounted to 67623, 71887, 65367, 

 48593, i.e., in the mean, 63368. This figure multiplied by five 

 yields 316840, and, if we are permitted to make use of this average 

 number, we may well say that the quantity of microbes transmitted 

 into the rabbits along with blood, was not very far ofi" this number. 

 We are, however, well justified in taking it somewhat higher, from 

 the fact that a portion of the bacteria in the blood are occurring in 

 twos, which will not be easily separated by mixing with gelatine, in 

 which they will give rise to but one colony. 



This relative scarcity of the micro-organisms of chicken-cholera 

 in the heart-blood of rabbits, newly dead., stood in a sharp contrast 

 to the relative abundance of these microbes in samples of the same 

 blood, taken from rabbits which had been left where they died 

 untouched, (say) for twelve, twenty-four, thirty-six, or 7nore hours. 

 In each case, where such a comparison was made — for that 

 purpose one portion of the rabbits, as used for the inoculations, 

 were examined soon after their death, and the other corresponding 

 portion at some time after their death ; but also on other occa- 

 sions, when I had an opportunity of thus comparing, — I could not 

 fail to be struck with the disparity of the heart-blood alluded to. 



On the other hand, it was repeatedly noticed that the capillary- 

 blood derived from cut surfaces of the liver, soon after the death 

 of the rabbits, contained incomparably more numerous bacteria 

 than the heart-blood derived from the same subject, and at the 

 same time. 



I must add that all the samples for microscopical examination 

 were derived in like quantities, and spread and stained on cover, 

 glasses in like fashion. From this it is evident that in rabbits 

 dead of " chicken-cholera," at the time of death or shortly after it, 

 the blood of the heart and main vessels carries only a relatively 

 small number of the bacteria, and that their relatively plentiful 



