Isle of Wight Disease in Hive Bees. 61 



nothing was known of Nosema, and therefore I was unaware of any risk, and 

 used the combs from which the bees had disappeared, when restocking the 

 apiary with purchased bees, and ' nothing happened.' " 



Beuhne is of opinion that " under ordinary conditions, that is, conditions 

 favourable to bees, the parasite is merely a casual inhabitant of the intestine 

 of the bee." 



General Conclusion Eegaeding Infectivity. 



The general conclusion to which the foregoing facts point is that Isle of 

 Wight disease, although probably an infectious disease, is one which requires 

 the coincidence of other and presently unknown external factors (besides a 

 specific organism) before the disease develops. The disease is not necessarily 

 conveyed by mere contact with contaminated hives or combs, or by feeding 

 upon contaminated stores. 



Explanation of Plate. 



Fig. 1. Section of the ohyle-stomaoh of a bee displaying symptoms of Isle of Wight disease. 

 Spores of Nosema are not present, and no young forms were found in this outbreak. 

 X 180 (Iron-hsematoxylin). 



Fig. 2. Section of the chyle-stomach of a bee infected with Nosema, but not suffering from 

 Isle of Wight disease. The stained spore contents came out as black dots in the 

 photograph, x 180 (Iron-hsematoxylin). 



Fig. 3. Portion of the teased chyle-stomach of a bee, showing detached cells, some contain- 

 ing spores of Nosema. Fresh preparation, x 180. 



Fig. 4. Fresh unstained preparation, showing Nosema spores lying free in the gut. x 180. 



Fig. 5. This shows the behaviour of a stock (E14) suffering from Isle of Wight disease. 

 Note the bees, incapable of flight, clustering on the hive front. Large numbers on the 

 grass cannot be seen, but some can be observed climbing up the leg of the hive. 



e.s. Chyle-stomach of bee. 



e. Epithelium lining chyle-stomach, 



sp. Spores and epithelium of chyle-stomach. 



(Issued separately, lith September 1916.) 



