214 SOME MINUTE ANIMAL PARASITES 



infected with N. apis from victims of " Isle of 

 Wight " disease, died in a short time. Subsequent 

 investigations proved absolutely the correctness of 

 their view, both with regard to the life-history of 

 the organism and its relation to the disease. The 

 life-history of the parasite and its action on the bees 

 may now be given in some detail. 



In many animal diseases there are distinct external 

 signs whereby the malady can be detected and 

 diagnosed. With the " Isle of Wight " disease, 

 better designated microsporidiosis, there is much 

 greater difficulty, for the bees present no external 

 symptom that can be described as universal. The 

 only feature at all constant is that, when the out- 

 break is at all severe, enormous numbers of bees die 

 within a very short time, and often the deaths appear 

 to be simultaneous. But in many cases certain 

 features can be recognized. When the bees are 

 infected with the N. apis, they are feeble and become 

 incapable of flight. Often their wings are dislocated, 

 and the unhappy victims creep about on the ground, 

 often with their abdomens trailing, and vainly 

 endeavour to launch themselves into the air by 

 creeping up some taller blades of grass or projecting 

 leaves. Others manage to reach the alighting board 

 before the hives, but are too enfeebled to crawl into 

 the interior, so remain outside, finally lose their 

 balance and fall on to the ground, there to perish 

 miserably of cold and hunger. 



Other infected bees manage to fly out of the hive, 

 and make some attempt to collect pollen or nectar. 

 But in their weakened condition the task proves too 



