278 SCIENCE PROGRESS 



in defending them from enemies. Migration to a district en- 

 tirely distinct in character, where other species of plants are 

 blooming, is therefore of immense advantage, and it seems 

 almost impossible to imagine an insect constituted on the lines 

 oi Apis surviving in India without this habit. 



The second feature is the fact that two of these species 

 confine their structure to a single comb. This is, of course, the 

 simpler and more natural arrangement and it is rather a 

 striking advance on the part of mellifica that has brought about 

 the eight or more parallel combs, instead of the one very 

 greatly extended comb of dorsata. The immense advantage 

 of this compact form, from the point of defence, is obvious, as is 

 also the habit of building in hollow places. 



Ill 



In Apis and one or two minor tropical genera closely allied 

 to it, specialisation has reached the stage in which the queen has 

 entirely lost the foraging instinct, together with the necessary 

 structural appliances. She does not build comb, nor undertake 

 the work of hatching and rearing the brood. The advantage 

 of this is, that her energies are concentrated on egg-production ; 

 she can turn out an enormous quantity of foragers and nursery 

 workers, and, as she remains always within the hive, her safety 

 is very much more assured. The benefit of this specialisation is 

 very evident, for queens frequently live four or five years, and, 

 although only two or three new colonies are started annually, 

 the race is able to take care of itself and increase under reason- 

 ably favourable conditions. The honey-storing habit, which in 

 principle is precisely the same as that of many plants, which 

 are able to survive long periods of drought, in a leafless 

 condition, by living on the stores collected by the leaves and 

 accumulated in the roots, enables sufficient workers to survive 

 the winter, so that the hive, when once substantially founded, 

 is a permanent institution. 



In the Bumble-bees, Bombus, however, specialisation is only 

 partial and the insect is strictly annual in its duration. Workers 

 are produced, in numbers varying from ten to thirty in the case 

 of the small Carder-bees, to as many as eighty or a hundred in 

 the Great Earth Bumble-bee. But there is not the constant 

 succession of workers which enables a number to survive 

 and assist the queen through the winter and early spring. 

 Worker Bumble-bees do not appear before June, and are all 

 dead by October. Rather more young queens are produced, 

 at the end of the summer, than in the case of Apis, and, on the 

 other hand, the males are not so over-predominant. After 

 pairing, the queens seek sheltered quarters in banks of moss or 



