38 THE EVOLUTION OF SEX. 



falls below the share which workers and queens obtain. The fatty 

 material, at first large, soon falls to about a third of that given to 

 the queens. Hence the percentage of glucose, except at first, is so 

 much larger than in the other two cases. 



It is not necessary, however, to go into details to see the import- 

 ance of the main point — that differences of nutrition, in great 

 part at least, determine the all-important distinctions between the 

 development and retardation of femaleness. Nor are there many 

 facts more significant than the simple and well-known one, that 

 within the first eight days of larval life, the addition of food will 

 determine the striking structural and functional differences between 

 worker and queen. 



Eimer has drawn attention to the interesting correlation exhibited 

 in the fact that a larva destined to become a worker, but converted 

 into a queen, attains with the increased sexuality all the little structural 

 and psychological differences which otherwise distinguish a queen. 

 Regarding fertilization as a sort of nutrition, he considers drones, 

 workers, and queens, as three terms of a series, and the same view 

 is suggested by Rolph. Eimer recalls some interesting corroborations 

 from humble-bees. There the queen-mother, awakened from her 

 winter sleep by the spring sun, makes a nest, collects food, and lays 



her first brood. These are not too abundantly supplied with nourish- 

 ment, the queen having much upon her shoulders; they develop 

 into small females, workers in a sense, but yet fe-tile, though only 

 to the extent of producing drones. By-and-by a second brood of 

 workers is born; these have the advantage of the existence of elder 

 sisters, are more abundantly nourished, and develop into large 

 females. Still, like the first brood, they produce drones, though 

 occasionally females. Finally, with the advantage of two previous 

 broods of small and large females, the future queens are born. The 

 above facts not only afford an interesting corroboration of the 

 influence of nutrition upon sexuality, but are of importance as sug- 

 gesting the origin of the more highly specialized society of the hive- 

 bee. 



(V) Von Siebold's Experiments. — With a somewhat different pur- 

 pose than that at present pursued, Von Siebold made a series of 

 careful observations on a species of wasps, A T e?nalus ventricosus. These 

 afford, as Rolph has noted, some valuable results in regard to the 

 determination of sex. In this wasp, the fertilized ova, unlike those 

 of hive-bees, develop into males as well as females; while the unfer- 

 tilized or parthenogenetic eggs may produce females in small per- 

 centage. From spring onwards, as warmth and food both increased, 



