31 



a mixture of honey and wax which indicates possibilities for growth 

 of moulds also on these combs. 



Another point of interest is the question whether the toxic substances 

 are secreted by the fungus in the substratum or found only in the 

 mycelium. If it could be shown that they do dissolve in the me- 

 dium serious consequences would arise when mouldy combs, even 

 if carefully aired and dried, are given the bees anew. The following 

 experiment is cited to show that mouldy wax, if not properly purihed 

 and separated from cocoons when melted retains its toxicity to bees. 

 The method of extracting the toxic substances was the one adopted 

 by Alsbekg and Black (1). 30 grams of mouldy material were melted 

 and digested 16 honrs with 150 c. c. of 95 per cent alcohol. The 

 extract was filtered and evaporated on the steam bath. The residue 

 was filtered leaving about 0.5 c. c. of an acid solution. 2 c. c. sterilized 

 water was added and the mixture given bees together with honey. 

 The results of the feeding experiment are given below. 



Series I. 



Jnly 12. The acid solution was mixed with 2.r> c. c. honey. 1 1 

 bees were caged. July 14-, Four bees dead; the remaining very 

 drowsy. July 16. All of them dead. 



Series II. 



July 17. 1 c c. of acid extract was obtained and mixed with 5 c. c. 

 honey. 8 bees were caged. July 18. No sign of disease could be 

 detected. July 19. Two dead ; one dying. July 21. All of them 

 dead. 



That the composition of the medium largely determines whether 

 the toxic substances are dissol ved or retained in the mycelium has 

 been made very plausible by the investigations of Alsberg and 

 Black. Penicillium stoloniferum grown on agar-agar medium was 

 found to render the media toxic to bees. 



When it is found that not only the moulds themselves but under 

 circumstances the products of their growth as well give rise to 

 paralysis it becomes necessary to mention the factors which condition 

 and prevent the growth of moulds in the bee-hive. A suitable 

 temperature, not to low, must prevail, and a certain amount of moisture 

 must be present if moulds shall do any damage among the bees 

 during winter and spring. That both of these condition s often are 

 fulfilled leading to a luxuriant growth of moulds is well known 



