11 



Howard obtains his best growth under the mica plate, which does not give 

 complete anaerobiosis. Howard's conclnsions are thus ac variance with 

 Cheyne's, and my own results fully corroborate those of the latter author. 



Howard states that ihe vitality of the spores of B. alvei is destroyed 

 when exposed to atmospheric air from 24 to 36 hours. In making his experi- 

 ments he took sterilized road dust and mixed it with the dry foul brood 

 masses from several cells which were previously dissolved is distilled water. 

 The mixture was worked dry, and spread on sheets of paper, and trial cul- 

 tures were made immediately and at intervals of every twelve hours for three 

 days ; and according to his results no growth occurred after 36 hours la 

 giving these results, Howard does not state whethtr he exposed the spores to 

 sunlight or diffused light ; nor does he mention the age of the dry foal brood 

 masses, which he used from several cells. These are points of considerable 

 importance, for as everyone knows the disinfecting power of ditect sunlight 

 ia much greater than diffused light, and the vitality of the spores from foul 

 brood masses of different ages varies considerably. This, I may add, has 

 been clearly shown by some of my experiments, subsequently described. In 

 my experiments, the spores obtained from a pure culture on the surface of 

 agar, were spread on cover glasses and placed in a glass chamber, so arranged 

 that a current of air was constantly circulating over them. This chamber was 

 exposed to the ordinary light of a room with six large windows, and a cover 

 glass was taken out every 24 hours and tested, to see if the spores would 

 grow. This experiment was continued for one month and at the end of that 

 time the spores still germinated rapidly. In another experiment, spores 

 spread on cover glasses were exposed to a very diffused light, simulating as 

 far as possible the amount of light which would enter a hive. Oover glasses 

 were taken oat from time to time and transferred to agar, in order to ascer- 

 tain if the spores were alive or not. The experiment was begun two years 

 and four months ago and from the last cover glass taken and placed upon the 

 surface of an agar plate a copious and typidal growth of B. alvei was obtain- 

 ed. Further, thin strips of filter paper, plunged into a bouillon culture and 

 allowed to dry, were threaded on a wire suspended in a wire basket and so 

 exposed that the air could freely circulate around them in the ordinary light 

 of a room. Trial cultures were made at intervals, and at the expiration of 

 6 months the spores from the paper germinated when the strips were placed 

 on the surface of agar. 



Again, a drop of bouillon containing spores was placed in a sterile tube 

 and allowed to dry ; and at the expiration of 124 hours (36 of which were in 

 sunlight at a temperature varying from 30° 37° 0) sterile bouillon was added. 

 The tubes were then placed in the incubator, asd in less thaa 24 hours a good 

 growth of the germs had taken place. 



From these experiments it will be seen that the results are directly at 

 variance with Howard's statement, as thty go to show that the vitality of 

 the spores of B. alvei is not destroyed by exposure to atmospheric air, with 

 or without sunlight, for even a much longer time than 24-36 hours, 



With regard to the aerobiosis of this bacillus, good growth has been ob- 

 tained in an atmosphere of hydrogen by Novy's method. Bnchner's method 

 also gave good results. The growths in the various media are very similar 

 to those produced under aerobic conditions, but with this difference, that the 

 surface growths are, as a rule, whiter in the hydrogen atmosphere. In 

 illuminating gas (water g+s) no growth occured ; but the spores were not 

 destroyed by the action of ihe gas ; for when the gas was let out of the Novy 

 jar, good growth ensued on all cultures. In acetylene gas, a restricted 



