Page:Popular Science Monthly Volume 64.djvu/109

Rh of which kind of egg she is about to lay next, and seeks the proper cell to deposit it in. There are, however, some further facts that show that the conditions may be more complicated than has been generally supposed.

It has been possible to introduce a virgin queen of an Italian stock into a hive containing workers and males of a German stock. These two kinds of bees are sufficiently different to be readily distinguished from each other. The Italian queen becomes fertilized by the German males. In consequence all the queens and workers that come from her eggs are hybrids, since they come from fertilized eggs, but the males or drones are nearly all of the same kind as the queen, which indicates that they have come from unfertilized eggs. Occasionally, however—and this is the point of special interest in the present connection—a few males appear that are hybrids, as Dzierzon long ago observed. Hence we must suppose that an egg has been fertilized, and despite this fact it has developed into a male. This conclusion may indicate, as Beard has recently claimed, that the sex of the egg must have been already determined, and was not altered by the accidental entrance of a spermatozoon.

In this connection it should be pointed out that Weismann and Petrunkewitsch found that out of 272 drone eggs that they studied there was one that had been fertilized. Whether it would have become a male or not, could not be determined; for it is said that the queen sometimes makes a mistake and deposits a worker egg in a drone cell. Indeed 'whole combs of drone cells may produce workers instead of drones.'

These are some of the principal facts that seem to show that the sex of the individual is predetermined in the egg. From the evidence Cuénot arrives at the following general conclusions: He thinks that in the great majority of animals the sex is determined in the egg and at latest when the egg is fertilized. In no instance, he claims; has it been shown that the sex of the individual can be determined later than fertilization. The classic examples, insects and frogs, in which it was supposed that external conditions acting on the later embryo determined the sex, have been shown to be capable of a different interpretation. It has been especially made clear, Cuénot claims, that a meager or an abundant supply of food has no influence on the determination of the sex of the embryo. He believes moreover that it is the egg and not the spermatozoon that determines the sex of the individual. In several insects, in Dinophilus, in pigeons, and in the winter eggs of aphids and of daphnids, this has been clearly shown to be the case. In other animals, as in the rotifers and in the social hymenoptera, the spermatozoon appears to have a determining influence. In the mammals the entrance of the spermatozoon may have only the same