60 



Wight Disease. There were two stocks in particular from which I could 

 procure spores at almost any time, yet these stocks showed only the normal 

 death-rate, and could not at any time be said to display symptoms of disease. 

 The theory that Nosema was the cause of Isle of Wight Disease did not seem 

 to fit the facts as observed in Lewis. It might, therefore, be profitable to 

 examine the results of the Cambridge investigation to see how far the main 

 conclusion is warranted. 



III. — Criticism of the Conclusion that Nosema is the Cause ; 

 OF Isle of Wight Disease in Bees. , 



1. If Nosema were the cause of the disease then Nosema ought to be 

 demonstrable in every bee suffering from the disease. But Dr Porter was 

 unable to find any stage of Nosema in some of the " crawling " bees which 

 I sent her in June 1913. On page 41 of the 1912 report is an, account of 

 66 cases investigated jointly by Drs Graham-Smith, Fantham and Porter. 

 Nosema was not found at all in 13 cases, spores were found in only 29 cases, 

 and so-called young stages in other 24 cases. The authors discount three 

 cases in which the bees arrived dead, though it is quite easy to find spores in 

 bees that haye been dead for months. They claim, therefore, to have found 

 Nosema in 53 out of 63 cases, or in 84 per cent, of the cases examined. 



If Nosema is present in every case of Isle of Wight Disease, it is some- 

 what surprising that it was not noticed by Imms or Maiden in 1907 and 

 1908. Both were searching for bacteria, and Dr Maiden in particular 

 claims to have exhausted this field. Nosema as compared with the average 

 bacterium is relatively large, and one has difficulty in believing that Maiden 

 could have failed to notice it if it were actually present. 



2. If Nosema be the cause of Isle of Wight Disease, the presence of the 

 parasite, at any rate in quantity, should always produce the disease. But 

 there is much evidence to show that Nosema may be present without producing 

 the characteristic symptoms of Isle of Wight Disease. Two such cases in 

 Stornoway have been mentioned above. We still have one of these stocks 

 under observation, and we can get spores of Nosema from it almost at any 

 time. I have frequently picked up bees entering this hive with pollen on 

 their legs, or nectar in their honey-sacs, yet on examination they displayed 

 heavy infection of Nosema in the spore stage. On page 50 of the 1912 

 report we read : " Spores in small numbers were found, however, in specimens 

 from several stocks in one apiary in Scotland. No symptoms of the disease 

 had previously been noticed, and none have appeared since." 



Maassen, writing in 1911,' states that Nosema can be found in most 

 ' Mitteil. a. d. K. Inolog. Aust, /. Land. u. Forttwutschaft, 1911, p. 50. 



