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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 purified
and separated from cocoons when melted retains its toxicity to bees.
The method of extracting the toxic substances was the one adopted
by ALsBERG and Brack (1). 30 grams of mouldy material were melted
and digested 16 hours 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.
July 12. ’The acid solution was mixed with 2.5 c.c. honey. 11
bees were caged. July 14. Four bees dead; the remaining very
drowsy. July 16. All of them dead.
Series II.
July 17. 1 cc. 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 dissolved or retained in the mycelium has
been made very plausible by the investigations of ArsBEnG and
Brack. 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
lemperature, 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 conditions often are
fulfilled leading to a luxuriant growth of moulds is well known
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