GENERAL RESUME. 247 



those of small size. Since the senses of sight and smell differ greatly in the 

 various groups of insects, the relative importance of the three attractive 

 factors will be modified accordingly. In a group of plants or a floriferous 

 individual or even in the midst of a cluster of flowers, odor can have little 

 effect, except in the rare instances when very fragrant flowers or clusters 

 are widely separated in such groups. The odor is not only general, but it 

 is naturally most powerful at the flower or cluster on which the insect is 

 working. Such conditions would not permit it to go straightway and with- 

 out an instant's hesitation to the next flower or head, and guidance by 

 color and form alone can explain the assured and rapid flight of bees in the 

 midst of flowers. This is confirmed by their behavior when the wind is 

 blowing, for they fly most easily with the wind, though this carries the 

 fragrance of the next flower sought away from them. Moreover, the readi- 

 ness with which they often drop from the midst of a plant or bush to fallen 

 corollas on the ground a foot or more below further supports the view that 

 odor is rarely a guide among flowers. However, it must be kept in mind 

 that such studies have so far been incidental and concerned with bees al- 

 ready habituated to the flowers concerned, except in some of the competi- 

 tion studies already given in chapter 3. 



LEARNING AND HABIT. 



It is possible at present to deal with learning and habit only in 

 the general qualitative manner so admirably exemplified in the work 

 of Lubbock, Mueller, Forel, Peckham, Buttel-Reepen, Detto, Lovell, Turner, 

 Frisch, and Knoll. The time has come for a comprehensive quantitative 

 attack on the learning process and its relation to the fixation and modi- 

 fication of habit, and one of the primary objects of the present book is 

 to clear the way for such investigation, as indicated earlier. In view of 

 their generalized mental organization, the ability of insects, and especially 

 the bees, to learn by experience is remarkable. This has been widely recog- 

 nized by experimenters in this field, though it has been doubted by some 

 who failed to take into account the qualities emphasized by Mueller, 

 namely, the shyness and lack of cleverness in unusual surroundings and the 

 all-powerful obsession for honey. The ease and rapidity with which habits 

 of landing and securing nectar are modified under changed conditions 

 indicate a great power of learning and a corresponding plasticity of 

 habit that is surprising. These qualities will probably be found to be 

 even more marked in the case of newly hatched or young insects, and it is 

 possible that the training of these will disclose new possibilities of learn- 

 ing and adjustment. As the work of Giltay shows, the selection of marked 

 individuals on the basis of different types of response opens a new vista 

 in this field, and permits the extension and refinement of our knowledge 

 of the mental powers of the species and group by means of the psychology 

 of the individual. 



MEMORY AND INTELLIGENCE. 



The Peckhams concluded that wasps have a very good memory, and 

 Forel stated that bees not only have memory for place but also for time, 

 a statement in accord with the views of Buttel-Reepen. Probably the 



