Nosema Apis and Isle of Wight Disease in Hive Bees. 19 
Wicht 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. Jt might, therefore, be profitable to 
examine the results of the Cambridge investigation to see how far the main 
conclusion is warranted. 
Il1l.—Criticism oF THE CONCLUSION THAT NOSEMA IS THE CAUSE 
or 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 have 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 Malden in 1907 and 
1908. Both were searching for bacteria, and Dr Malden 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 Malden 
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 Wosema 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 
1 Mitteil, a. d. K. biolog. Aust. f. Land. u. Fortswistschaft, 1911, p. 50. 
