620 LIFE : OUTLINES OF GENERAL BIOLOGY 



examples of instinctive behaviour, it is useful to take account of 

 Rosch's precise study of the gradual change of behaviour in worker 

 honey-bees. By marking individuals in an observatory hive he was 

 able to follow the apprenticeship of the worker-bees and their 

 gradual promotion, so to speak, from one kind of duty to another, 

 in the course of their short summer life of a month or six weeks. 

 The newly emerged workers are turned to the task of preparing and 

 cleaning wax cells in which the queen will lay eggs. After a few days 

 they pass, or are promoted, to the status of nurses, watching over 

 the young bees in their cells. At first they attend only to the older 

 larvie, supplying them with pollen and honey which other workers 

 bring in ; but later on they are allowed to look after the very young 

 larvae, which require a special nutritive fluid secreted by their 

 nurses. This milky fluid comes from the upper pair of salivary glands 

 in the head, which begin to function at this time, about the tenth 

 day of winged life. They are not developed in queens or drones. A 

 few days later, when the worker has been at work for about a 

 fortnight, she leaves the brood-comb, or "nursery", and spends a 

 week in the general service of the hive — in cleaning away refuse, 

 distributing and storing food, and in similar duties. Trial flights in 

 the open may also be made, but on these first ventures no pollen 

 or nectar is collected. Finally, at the age of about three weeks after 

 emergence, each worker is assigned the last of its indoor tasks, that 

 of acting as guardian at the gate, preventing the entry of strange 

 bees or other insects. Having duly discharged this duty, the worker- 

 bee devotes all its remaining time and strength to the work of 

 collecting nectar and pollen from the flowers. But here, as Frisch 

 has proved in detail, confirming Aristotle's observation and Darwin's 

 remark that "bees are good botanists", there is often a singularly 

 monotonous efficiency. F'or when a bee has found a profitable and 

 abundant species of flower, it may keep to that for the whole of its 

 short outdoor life without ever entering another kind of blossom. 



As Rosch is a scrupulous observer, his account of the bee's suc- 

 cession of activities must be carefully considered. There are several 

 points of importance. F'irst, there appears to be a social control 

 which leads the worker from task to task, though there is also the 

 physiological change, as in the activation of the salivary glands, 

 which makes the bee fit for a particular task when she reaches a 

 certain age. Second, there is the occurrence of trial flights in the 

 open before any actual collecting begins. This suggests that the bee 

 must not be thought of too mechanically, as if it were an automatic 

 machine compelled by the release of successive springs to a definite 

 series of activities. Thirdly, there is here a good illustration of the 

 economising of energy that is made possible by a social organisation. 

 Every day of the short life is utilised by the graded succession of 

 duties. 



