12 



growth occurred. In fermentation tubes, growth occurred both in the open 

 and in the closed arm of the tubes. No gas was formed, the bouillon in the 

 closed arm was uniformly turbid. Thus B alvei is a facultative anaerobe. 



Production of Alkali In ordinary bouillon a slight amount of ammonia 

 is formed. Control bouillon did not give the Nesaler test. In glycerine 

 and the sugar bouillons, there is no trace of ammonia. Cheyne's cultures 

 are faintly alkaline, both before and after inoculation in meat infusion. 

 Elamann states that ammonia is produced, 



Acids formed A varying amount of acid is formed. All the sugar 

 bouillons give an acid reacton. 



Formation of Pigment. On potatoes, a yellowish growth is produced ; 

 on all other media, the surface growth is white. 



Development of odours Cheyne states that gelatine cultures give off an 

 odour of stale, but not ammoniacal urine, or what may be better described 

 as a shrimpy smell ; and this peculiar odour has been formed by Cheshire to 

 be distinctive of diseased larvae. Klamann and Howard both state that a 

 peculiar odour resembling that of the diseased larvae may be noticed in arti- 

 ficial cultures. 



The Efects of Desiccation I have already noticed, under the head of 

 " Relation to Free Oxygen," that the spores of B. alvei have considerable 

 vitality in withstanding desiccation. My experiments prove conclusively 

 that the spores are extremely hard to kill by desiccation and in this respect 

 resemble those of anthrax, which are known to resist thorough desiccation for 

 a number of years. One experiment which shewed this characteristic was as 

 follows : An agar plate completely covered with a typical growth of B. alvei 

 was allowed to dry out completely, and was left exposed to the ordinary light 

 of the room for 7 months, and at the end of that time, a portion of the film 

 was scraped off with a knife, placed on suitable medium and incubated, with 

 the result that a typical growth immediately ensued. 



Spores on cover glasses were exposed to September sunlight (Latitude 

 43) for varying periods of time, and growth occurred after 4, 6 and 7 hour's 

 exposure. The age of the spores varied from 6 days to 18 months; and 

 spores 3 months old were not killed by 7 hours' exposure. 



Thermal Eelations. 



Maximum for Growth. The maximum for growth is about 47°C. At 

 44°C., good growth occurs ; but at 50°C., growth ceases. Experiments on 

 maximum for growth were performed on gsrms isolated from a number of 

 different places, and little oe no difference was noticed in their behaviour 

 when incubated at the temperatures mentioned. 



Optimum for Growth. The optimum for growth is about 37.5°C. for 

 all media except gelatine. This has been determined by Cheyne & Eisen- 

 berg (39). On gelatine the best results are, of course, obtained from higher tem- 

 peratures ; but as 10% gelatine melts at about 24°C., 22°C cannot be exceeded. 



Minimum for Growth. Cheyne says that the bacilli do not grow below 

 16°0. I have, however, occasionally obtained growth at 14°C. on the surface 

 of agar ; but it has been extremely slow. The spores will not germinate at 

 this temperature. No difference, under this head, is apparent in germs 

 obtained from different countrifs. 



Thermal Death Point. This is a very important matter, becauEe in the 

 heating of wax and honey from colonies suffering with foul brood, it is neces- 

 sary to know the temperature that will destroy spores and thus prevent the 

 infection of other bees ; and unfortunately a considerable discrepancy exists 



