The conclusions, then, reached in this paper are, that in many cases the differences between fertile and infertile insects are due to the quality or quantity, or both, of the food given to the larvæ. This conclusion is of worth, since it is supported by Huber, Smith, Woodbury, and others; though these naturalists only apply it to the social bees. The suggestion of Professor Wyman, that the difference in development is due to the difference in the time the eggs are laid after fertilization, seems to be opposed to facts; especially to the experiment of Kleine, who reared worker-larvæ into queens by feeding them on royal food. The other conclusion is, that the neuters represent the type from which the true males and females have diverged; that in those cases where food is powerless, the neuter retains its immutability for the reason that its development is arrested at a certain stage; that is, it does not go beyond the state reached by the typical progenitor, while the perfect males and females go beyond this stage, and that the differences between them and the neuters were inaugurated at this time; that changed conditions have been potent in producing such differences; that the differences are only inherited at that advanced period of progression in which they were initiated. In other words, to render this conclusion plain to the general reader, we believe that if the neuter-worker of the white ant, for example, were to progress in development, it would turn into the fertile female; if the neuter soldier of the white ant were to continue on the line of development, it would become a fertile male. This does not give support to the theory that the worker and soldier are immature male and female; that they are the perpetual babies, while the perfect insects are adults—since we believe that in their way the neuters are as adult as their parents. This proposition may be rendered clearer by a symbol, which may be represented by the letter Y. The stem of this letter will stand for the typical insect represented at the present day by the neuter, and the two arms, respectively, will represent the male and the female, which, after the typical insect reached a stable form, diverged into new routes of progression.
At some future time we hope to work out this subject more elaborately, and, from the observations and facts already collected, it is believed that the theory can be defended if not vindicated. Our present purpose, however, has been accomplished—to introduce to the general reader a subject which has perplexed, and still perplexes, our greatest naturalists.
