DISEASES OF BEES 9 



limiting infective dose in Sturtevant's experiments was considerably 

 smaller than that used in the above described experiments may be 

 because B. larvae rapidly loses virulence following cultivation on 

 laboratory media. It seems highly probable that a few resistant 

 endospores become established in the guts of very young larvae, 

 and that once established they resist the digestive processes until 

 conditions which favour their development arise, while the less 

 resistant vegetative cells of the organism are rapidly killed under 

 identical conditions. 



It is of interest that, in these experiments, relatively large doses 

 of vegetative cells of B. larvae would not cause American foul brood 

 to develop. If a method of keeping this organism in the vegetative 

 stage could be devised, then the control of the disease in infected 

 colonies might be simplified. Unfortunately the possibility of doing 

 this seems rather remote. 



The results obtained have shown that American foul brood is 

 the most prevalent brood disease in England, that it is a distinct 

 disease caused by a resistant spore forming bacillus, and that a 

 mass inoculum of spores of the organism is required to initiate 

 the disease. So far no attempts have been made to study methods 

 of controlling this disease. The very nature of the disease makes 

 the possibility of obtaining a simple chemical remedy an 

 extremely doubtful one, and it is not proposed to encourage any 

 false hopes in this direction. Practical measures of control are 

 known and the value of these under the conditions which pertain 

 to this coimtry must be determined. 



Addled brood 



The fact that this complaint should occupy such a prominent 

 position with reference to the total number of brood diseases was 

 not foreseen when the investigation commenced. Should the 

 treatment of this very prevalent disease be as simple as is indicated 

 by preliminary experiments we may well be pleased that so much 

 of the disease is of this type and not so-called " foul brood." Before 

 discussing the results obtained in practical experiments it is essential 

 that brief reference be made to the somewhat scanty pertinent 

 literature. 



Throughout the past few decades numerous references have been 

 made in the German literature to " Eitaubheit," a disease of bees 

 in which apparently normal, fertile queens lay eggs which never 

 develop. There is no adequate equivalent in the English language 

 for this name and it is best expressed as Addled egg disease, the 

 eggs being known as "Addled eggs" (Taube Eier). References to 

 the condition in which brood dies at some stage prior to reaching 

 maturity have been far less mraierous in comparison. As far as 

 I have been able to ascertain the late Dr. Leuenberger was the 

 first to describe Addled brood though he did not actually employ 

 this term. In one case of Eitaubheit he observed that a small 



