768 THE POPULAR SCIENCE MONTHLY. 



with reference to wasps* viz., if wasps are taken away from 

 their nests and liberated over water, they fly toward the nearest 

 land, although their nest is in the opposite direction. In liberat- 

 ing the pigeons from the boat this reaction was tested a great 

 many times and never failed. 



The tracings speak too plainly for themselves to require further 

 comment. If any are able to extract " direction-sense consolation " 

 out of them, they are entirely welcome to it. 



The criticism naturally arises at this point that the pigeons are 

 not trying to find home at all. They may be flying for pleasure 

 or exercise. Two things may be said in reply : First, theories of 

 " direction-sense " have been based upon the air-line course which 

 a pigeon has been supposed to take, " after getting his bearings," 

 from place of liberation to loft. This, as we have seen, comes 

 only after training. In the second place, after a little observa- 

 tion, it is easy to distinguish from the sportive cavortings for 

 pleasure the eager darting flight of search. 



If, however, they fail to give evidence of " direction-sense," 

 may not such tracings show something of even greater impor- 

 tance ? All animals, from amoeba to man, spend a good share of 

 their time searching for something or other. May there not be a 

 fundamental logic of search as universal as the search itself ? 

 Naturally, if this is so, those animals whose life depends most 

 closely upon finding the objects of their search would come to 

 have the power and the logic of search most highly developed. 

 We may then ask. What is the path or curve of logical search ? 

 It could hardly be a straight line, since the effort necessary to 

 search must have a tendency to cause any animal to search over 

 nearest ground first, inasmuch as turning or looking around is 

 easier than moving the body ahead as far as the animal is able to 

 see or feel ahead. We see this exemplified in the circling of 

 hawks and the circling of dogs when starting out to cover a field. 

 It could not be a circle, however, in case of an animal with mem- 

 ory to avoid covering the same ground twice. 



To test the matter experimentally, a number of people kindly 

 drew for the writer the path each would take to find an object, 

 the proximity or direction of which is unknown. The object is 

 supposed to lie upon a uniform field. Types of the curves handed 

 in are given in Figs. 5 to 8. Undoubtedly the logical curve is the 

 one submitted by Prof. Story (Fig. 5). It will be recognized to 

 be a peculiar spiral, the involute of a circle, the characteristic of 

 which is that the convolutions are always the same distance apart. 

 This distance will be, of course, twice the distance at which the 

 object is visible. The curve given by the majority is drawn in 



* Loc. cit.^ p. 17. 



