FOSEMA-DISEASE. 29 



repeated. Out of 138 bees in one set of four cages 125 (91 per cent) 

 were dead at the end of one week. In the other set of four cages out 

 of 136 bees confined 98 (72 per cent) were dead at the end of a week. 



On December 8 a check experiment was begun. In each of two 

 cages bees taken from healthy colonies were confined and kept at 

 room temperature. At the end of one week out of 59 bees confined 

 5 (8 per cent) had died. 



Out of a total of 472 diseased bees confined 393 (83 per cent) were 

 dead at the end of one week, while out of a total of 59 healthy bees 

 kept under similar conditions only 5 (8 per cent) were dead at the 

 end of a week. Although such experiments are subject to great 

 variation and should be repeated many times for definite results, yet 

 the difference between 83 per cent of loss in the case of infected bees 

 and 8 per cent of loss in the case of healthy ones is sufficiently great 

 to justify the conclusion that the heavily infected bees under the con- 

 ditions of the experiment possessed less endurance than the healthy 

 ones. These results indicate that weakness in a colony may result 

 directly from infection among the workers. 



Throughout the investigations which have been made on the dis- 

 ease, therefore, evidence has been obtained indicating that weakness 

 results not from the infection of the queen, drones, or brood, but of 

 the workers. 



RESISTANCE OF NOSEMA APIS TO HEATING. 



NOSEMA APIS SUSPENDED IN WATER. 



Preliminary results indicating the minimum amount of heating 

 that is necessary to destroy Nosema apis were given in an earher 

 paper (White, 1914). Other experiments have been performed. In 

 conducting the experiments a suspension was made in water of the 

 crushed stomachs and intestines of Nosema-infected bees. This 

 suspension was distributed in test tubes in such a dilution that the 

 amount in each tube contained the infective material of from 5 to 10 

 bees. The tubes were stoppered and heated at different degrees of 

 temperature by immersing them in water. Colonies free from infec- 

 tion were inoculated with the heated material and the results noted. 



Table VI summarizes some of the experiments made with the 

 results obtained. 



