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Beekeeping 
Sex determination. 
The determination of sex is one of the most earnestly 
debated questions in zoology. Numerous theories have been 
proposed, most of which are not now seriously considered. 
From the observations and conclusions of Dzierzon and other 
observers it was long held that sex in bees and similar forms 
(ants and wasps) is determined by the presence or absence 
of fertilization. These species were seemingly an exception 
to the phenomenon observed in most species. Of recent 
years, sex determination has been the object of numerous 
investigations and it is now quite generally accepted that 
sex is inherited in accordance with the same laws which govern 
other phenomena of inheritance. It is, of course, impossible 
to attempt to record here or even to outline the observations 
which lead to this theory or to elaborate the theory, as has 
been done by various authors. It is now held that one of 
the chromosomes (the bearers of hereditary characters) of 
the sex cells bears the sex-determining character. If we 
take into consideration the important fact that not all the 
eggs of an unfertilized (drone-laying) queen hatch, then the 
bee does not appear as an exception in Nature. It seems 
clear, however, that the statement of Dzierzon that all the 
eggs in the ovary are male eggs cannot be accepted and it is, 
in fact, not improbable that the eggs destined to be females 
die for want of fertilization, while the eggs destined to be 
males, not requiring fertilization, are capable of development. 
It should be understood that the casting of doubt on Dzier- 
zon’s theory of sex determination does not invalidate his 
theory in so far as it pertains to the development of males 
from unfertilized eggs. 
In view of the fact that drone eggs are usually deposited 
in the larger cells, the theory has been advanced that the 
pressure on the abdomen of the queen when she is about to 
lay an egg in a worker cell, by some reflex, causes the sper- 
matheca to open, thereby enabling the egg to be fertilized. 
This is known among American beekeepers as the Wagner 
theory. Since fertilized eggs may be laid in comb foundation 
