HOSEMA-DISEASE. 



37 



RESISTANCE OF NOSEMA APIS TO DIRECT SUNLIGHT. 



RESISTANCE WHEN DRY. 



Petri dishes (fig. 6) which were smeared with the crushed stomachs 

 of Nosema-infected bees were exposed to the direct rays of the sun. 



Fig. 6.— Open Petri dish. One-half of the dish, either top 

 or bottom. 



After intervals reckoned in hours healthy colonies were inoculated 

 with a suspension made from the dishes which had been exposed. 

 Table XVIII summarizes the experiments and the results obtained. 



Table XVIII. — Resistance of Nosema apis when dry to direct sunlight. 



Date of inoculation. 



Period of 

 exposure 

 to sun. 



Results of inoculation. 



Aug. 2, 1915.. 

 Aug. 21, 1914. 

 Aug. 2, 1915. 

 July 28, 1915. 

 Aug. 27, 1914. 

 Aug. 23, 1915, 

 Aug. 20, 1915. 

 Sept. 2,1914.. 

 Aug. 25, 1915. 

 Sept. 3, 1914.. 

 Sept. 14, 1915 

 Aug. 17, 1915. 

 Sept. 10, 1915. 

 Aug. 19,1915. 

 Sept. 11,1915 

 Aug. 24, 1914. 

 Sept. 13, 1915 

 Aug. 4, 1914.. 

 Sept. 16, 1915 



Hours. 



2 



5 



5 



8 



10 



13 



15 



15 



17 



20 



29 



15 



17 



18 



21 



22 



32 



34 



35 



Nosema infection produced. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 

 No infection produced. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



The results in Table XVIII show that Nosema apis was destroyed 

 in the experiments recorded in from 15 to 32 hours' exposure to direct 

 sunhght. 



It will be readily appreciated that the time that Nosema apis will 

 resist the destructive effects of the sun's rays will vary largely accord- 

 ing to the intensity of the rays, the heat present, and the thickness of 

 the layer of infective material exposed. 



DESTRUCTION IN WATER. 



In experiments made for the purpose of determining the time re- 

 quired to destroy Nosema apis suspended in water, an aqueous 

 suspension of the crushed stomachs of about 10 bees was poured into 

 each of a number of Petri dishes (fig. 6) and exposed to the direct 



