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ENTOMOLOGY 
mstinct in favor of such more precise terms as phototropism, 
geotropism, etc.; though the term imstinct remains useful as 
applied to an action that is the resultant of several tropic 
responses. 
The modern student of instincts aims to resolve them into 
their component reflexes and to determine as precisely as pos- 
sible the influence of each reflex component. Thanks to the 
labors of a great number of skilled investigators, we are no 
longer satisfied to class an action as “ instinctive’ and then 
dismiss it from thought; for now we are in a position to 
analyze the action, and may hope to explain it eventually in 
terms of the physical and chemical properties of protoplasm. 
3. INTELLIGENCE 
Though manifestly dominant, pure instinct fails to account 
for all insect behavior. The ability of an insect to profit by 
experience indicates some degree of intelligence. 
Take, for example, the precision with which bees or wasps 
find their way back to the nest. This is no longer to be 
accounted for on the assumption of a mysterious ‘‘ sense of 
direction,” for there is the best of evidence for believing that 
it depends upon the recognition of surrounding objects. 
When leaving the nest for the first time, these insects make 
“locality studies,’ which are often elaborate. Referring to 
Sphex ichneumonea, the Peckhams write: “ At last, the nest 
dug, she was ready to go out and seek for her store of pro- 
vision and now came a most thorough and systematic study 
of the surroundings. The nests that had been made and then 
deserted had been left without any circling. Evidently she 
was conscious of the difference and meant, now, to take all 
necessary precautions against losing her way. She flew in and 
out among the plants first in narrow circles near the surface 
of the ground, and now in wider and wider ones as she rose 
higher in the air, until at last she took a straight line and 
disappeared in the distance. The diagram [Fig. 291, A] 
gives a tracing of her first study preparatory to departure. 
