472 THE POPULAR SCIENCE MONTHLY. 



of the royal food on the inner margin of the worker cell and produced 

 queens. With bees, then, we see that the neuter is only a female with 

 the reproductive organs partially developed, a conclusion further en- 

 forced by the fact that the neuter sometimes even lays eggs which 

 develop into the drone or male bee. In this case then, at least, it may 

 be said that the fecundity or sterility of bees depends almost entirely 

 on the nature of the food given to the larvae. With the true ants 

 also, the so-called neuter is only a partially developed female, although 

 there are no recorded observations to show that the difference between 

 the fertile and the infertile insect is due to difference in food. 



To advance now a step further : insects, originally, were either 

 male or female ; there were no neuters. For reasons presently to be 

 given, we conclude that the males of even social insects, in addition to 

 the duty of fecundating the female, also undertook the duty of defend- 

 ing the nest against warlike intruders. It may be also safely con- 

 cluded that originally the females of even social insects, in addition to 

 the duties of maternity, also undertook the labors of building the nest 

 and taking care of the young customs that still prevail more or less 

 with many insects. Thus, the females of the solitary bees, after im- 

 pregnation, hybernate during the winter. With the warm clays of 

 spring they awaken, build their nests, and die. Among wasps a simi- 

 lar state of things obtains. When the winter approaches, the entire 

 colony, with the exception of a few pregnant females, dies. In the 

 spring these females begin building a new nest, laying eggs, and so 

 producing an efficient corj)s of assistants to aid them in their future 

 labors. 



Supposing, then, that originally the females undertook most of the 

 work now done by the neuters ; supposing, also, that at the beginning 

 of spring there are only a few females, or even one female, to com- 

 mence the work of building the nest and feeding the future progeny. 

 With many duties to perform, it is not unwarranted to conclude that 

 some duties may not be completely performed. The immediate suc- 

 cess of the colony depends, not so much on the number of males or of 

 females, as on a body of efficient assistants. Now, when one or a few 

 insects have to feed many, some of the larvte receive an abundance, 

 some barely a sufficiency of food ; and, on the theory previously ad- 

 vanced, we may see how neuter insects arose. The fact that quality 

 as well as quantity of food is essential to future fertility does not add 

 to the difficulty, since, as it takes more time to produce the highly nu- 

 tritious than the somewhat less nutritious food, the conditions are still 

 the same. If efficient assistants could be produced at a less expendi- 

 ture of labor and in a shorter time than females, a supposition coun- 

 tenanced by facts, natural selection begins to work. In a given neigh- 

 borhood those insects which produce a corps of assistants soonest, and 

 with least expenditure of labor, will stand a better chance of obtaining 

 food of surviving than those insects which give the same amount 



