BY DR. OSCAR KATZ. 533 



Own Exjjeriments. 



In my official reports full details (with illustrations) are fur- 

 nished about the experiments undertaken by me with a view to 

 obtaining what information was considered by the Commission 

 as worth having. Here it may suffice to give a resume of their 

 arrangements and their results. 



Generally speaking, such experiments were conducted : — 



A. On infected and uninfected rabbits mixed together 



I. In wooden hutches, either with wooden bottoms or 

 wire-netting bottoms. 

 II, In enclosures containing artificial burrows. 



B. On intact rabbits placed 



III. In boxes or hutches, in which rabbits had died from 



" chicken-cholera." 



Ad I. 



(a) On September 3rd, 1888, ten full-grown rabbits were fed,* in 

 separate cages, on cabbage-leaves to which was added a small quan- 

 tity of virulent broth-culture of the chicken-cholera microbes. f This 

 quantity was 2| ccm. each for eight of the ten, 1 ccm. each for the two 

 remaining ones.ij: Soon afterwards, when all the food had disappeared 

 except in one cage, where only about half was eaten, the ten rabbits 

 were placed, in the proportion of one to two, with tiventy uninfected 

 rabbits, of which six were only half-grown, in eight hutches, as 

 follows -.—six hutches (measuring in the clear inside 23" x 18" x 18" in 



* Whenever, during- the course of my experiments, rabbits were to be fed on " chicken- 

 cholera"-contaminated food, I adopted the precaution of starving them to some blight 

 extent beforehand, in order to induce them to eat the infected meal given to them more 

 readily. In spite of this arrangement it sometimes happened that the one rabbit or 

 another was slow in touching the food, or finishing it up. Wild rabbits, when suddenly 

 penned up in hutches, are naturally very shy and suspicious at first. 



t In order to be sure on this and all other occasions, when green leaves were used, that 

 the infective material adhered firmly to the food, and that the danger of the broth 

 becoming detached or perhaps lost, while the rabbits were eating, be avoided as much 

 as possible, each portion was prepared on a soup-plate, where the culture, which was 

 sprinkled out of a fine-pointed measured glass-tube, was placed between leaves or portions 

 of such, and these repeatedly pressed down, and turned by aid of flat wooden sticks. 



J The history of the culture employed is as follows :— Colony from virulent blood of a 

 rabbit (fed on culture), 10/vm. 1888 = 1. generation ; stick-culture in 6 p.c. rabbit-broth- 

 gelatine, 14/vin. = IL generation; stick-culture, 18/vm, = III. generation; rabbit-broth 

 culture, 1/ IX = IV; generatiou. The latter, when used September 3rd, had been since in 

 thermostat at 33-35° C. for two days. 



