BY DR, OSCAR KATZ. 619 



My experience as to the effect which it has on fresh wild 

 rabbits, when they are given to eat food contaminated with virulent 

 chicken-cholera bacteria — this kind of treatment having naturally 

 come largely and repeatedly into operation, as may be seen from 

 tlie various experiments described in the following — may thus be 

 summarised. 



Small quantities of freshly prepared broth-cultures (1 ccm.- 

 3 ccm.) of the microbes of chicken-cholera, or of blood derived 

 from animals dead from the disease, added to food (green stuff, as 

 cabbage- or barley-leaves ; dry food, as bran) and consumed by 

 fresh wild rabbits, caused the death of the animals with few 

 exceptions. The time which, in this mode of infection, lay between 

 feeding and death, fluctuated in the majority of instances between 

 18 and 25 hours; in others, more time elapsed until death fol- 

 lowed ; one full-grown robust rabbit, fed on bran with 1 ccm. of 

 virulent broth-culture, held out for about 3|^ days before it died 

 (from " chicken-cholera"). 



On the other hand, it was now and then, but comparatively 

 seldom, observed that fresh wild rabbits (also one tame one), which 

 had partaken of food contaminated with as much as 1 ccm. -2 ccm. 

 of fresh broth-culture, did not at all succumb subsequently, and 

 if so, not to "chicken-cholera." 



In about half the number of instances I am inclined to ascribe 

 the reason for these failures to the circumstance that the respective 

 rabbits, although having been somewhat starved before, waited for 

 hoars before eating of the food (green leaves), and that, in conse- 

 quence, the infectious matter on it was exposed to the drying effects 

 of a summer temperature, disastrous to the microbes. In this way, 

 it may be urged, the virulence might have been lost altogether, or 

 if a certain portion of active material was preserved, it was perhaps 

 not sufficient to infect by way of the digestive organs. 



Such an explanation, however, cannot be adduced in favour of 

 four other cases (three wild rabbits fed on 1 ccm. of broth-cul- 

 ture ; one tame rabbit fed on about l^^ccm.) ; nor can it be main- 

 tained that in those cases the quality of the material employed was 



