78 ORIENTAL PLAGUE chap. 



Williams and myself have published in the Lancet (1902) the 

 results that have been obtained in one of the London docks with a 

 large number (60) of cultures of the microbe (bought directly of 

 Danysz), as also with the bodies of guinea-pigs, mice, and rats dead 

 after subcutaneous injection with the microbe. The cultures — bread 

 soaked with broth emulsion of the microbe — as also the infected bodies 

 had been removed and eaten by the dock rats, but neither have any 

 dead rats been found in consequence, nor was the number of the 

 dock rats noticeably reduced. Other observers who have experi- 

 mented in the same manner have also had purely negative results. 

 In some instances undoubtedly positive results, i.e. destruction of 

 rats by placing infected materials (bread soaked in culture), have been 

 achieved ; while in still other instances it was shown that not only 

 is the breed of rats an important factor, but that even the same 

 breed of rats coming from different localities are affected differently. 



Quite recently, owing to an advertisement that had appeared 

 in the Times and in the Meat Trade Journal, I have bought a tube 

 of Danysz culture at the offices of the "Danysz Eat Microbe 

 Company" in Leadenhall Street, London. The experiment of 

 feeding rats was strictly carried out according to the printed 

 directions : viz. the whole of the contents of the agar slope — the 

 growth, as also the agar itself — were emulsified in and well mixed 

 with broth, and in this emulsion bread was soaked. This was 

 then given as food to three white rats. The animals had eaten up 

 the whole within the next few hours. The result was this : one 

 rat died after two weeks, the other two survived. With a fair dose 

 of the same culture a rat was subcutaneously injected at the same 

 time that the food was being prepared ; this animal died after four 

 days, thus showing that the culture sold to me was not very 

 virulent. If the culture had been really of normal virulence, the 

 animal would have been dead within two days. But the fact 

 remains that this culture was sold by the Danysz Company as 

 capable of destroying rats by feeding, which character it only partially 

 possessed, as was proved by the experiment. 



The Danysz bacillus behaves in gelatine and agar surface plates 

 and in gelatine and agar streaks exactly as the microbes of the 

 coli group, and these need not be further detailed. It produces 

 gas in glucose gelatine shake culture, the colonies extending all 

 through the gelatine ; it causes acid and gas production in 

 MacConkey fluid, but less than B. coli communis or B. Gaertner * 



