352 Experimental Zoology 
the worker cells that are very numerous; the drone cells that 
are much fewer in number; and the royal cells, of which there 
are, as a rule, only a very few. It has been shown both by di- 
rect observation and by experiment that the eggs laid in worker 
cells and in the royal cells are fertilized. These eggs produce 
females only. In the worker, the female sexual organs never fully 
develop. The eggs laid in the drone cells are unfertilized, and 
give rise to the drones or males. Rarely a queen may make 
a mistake and lay a fertilized egg in a drone cell, where it be- 
comes a worker; or lay a drone egg in a worker cell, where it 
becomes a drone. Evidently, then, the sex is not determined by 
the character of the cell, but by the presence or absence of the 
spermatozo6n. 
A worker egg can be changed into a queen if the young larva 
is supplied with the food given to the young queens. This can 
be accomplished artificially by placing some of the royal jelly 
taken from a royal cell (where it exists in excess) in a worker cell, 
containing a young maggot not more thanaday ortwoold. The 
bees will then continue to supply this cell with the royal jelly, and 
will break down the neighboring cells, destroying their inmates 
and thus make a larger, royal cell around this nouveau riche 
member of royalty. A drone egg cannot be changed into a 
worker or into a queen, although an exceptionally large male 
may be produced by feeding on the royal nutriment. 
When a queen has become old and has used up all of the sperm 
in the spermatheca, she can produce only drone bees. Also 
when a young queen is prevented from leaving the hive she 
produces only drones; for it appears that union with the males 
cannot take place within the hive. Workers also have been 
known at times to lay eggs which produce only drones. These 
and other facts led Dzierzon, in 1845, to formulate his famous 
theory. The substance of his view has already been given. He 
stated that a queen must be fecundated if she is to produce 
new queens and workers; that drone eggs are not fertilized; but 
that worker eggs and queen eggs are always fertilized. Dzier- 
zon also discovered that during copulation the eggs in the ovary 
