HISTORICAL AND EXPERIMENTAL STUDY OF HOMING. 11 



It will be seen from this table that Claparede's treatment is far too broad 

 to be of particular service to us in discussing the narrow division of the field 

 of orientation which especially interests us in the present paper. Claparede 

 includes in his discussion both vertebrates and invertebrates, both proximate 

 orientation and distant orientation, and includes under the latter term all 

 of the phenomena of migration. In our historical summary we shall deal 

 with homing in vertebrates where the goal is "already known." At the outset 

 it seems best to divide the subject of homing into two parts: (a) proximate 

 orientation and (6) distant orientation. 



PROXIMATE ORIENTATION. 



The term proximate orientation ought to be understood as referring to the 

 process of finding the goal (since we are in need of some general term covering 

 nest, burrow, cote, etc., it seems well to let the word goal refer to any of these) 

 when the goal itself directly and immediately stimulates the receptors of the 

 animal. In other words, in proximate orientation vision, olfaction, audition, 

 or some other distance receptor is being immediately stimulated by the goal. 

 We might illustrate the process of proximate orientation by citing the case 

 of the young bird which does not go out of sight of the goal to feed, and of 

 young mammals which stay within call of the parent. It might be equally 

 well illustrated in cases of animals with keen smell, which apparently can 

 journey quite a distance away from the goal and still return to it by reason of 

 the olfactory stimuli which emanate from it. 



An interesting case of proximate orientation occurs thousands of times in 

 the course of a single evening on Bird Key. As has been mentioned, the sooty 

 tern often flies around the island at night. When it is remembered that the 

 island is quite small, that there are probably 30,000 sooties there, and that they 

 nest oftentimes not more than 10 inches apart, the problem of their return at 

 night after these short journeys becomes a puzzling one. As a matter of fact, 

 the bird hovers over the nesting area giving out his call ; he is answered by his 

 mate and young and is thus guided to the nest, often on dark nights. In this 

 paper, then, proximate orientation will refer to those cases where orientation 

 is effected through the action of a stimulus which emanates from the nest 

 (sound, light, olfactory particles, etc.).* 



DISTANT ORIENTATION. 



Distant orientation involves always a return to the goal from a distance 

 too great for the goal itself to function as a direct stimulus to any known recep- 

 tor of the animal. It is obvious that the return in such cases can be effected 

 only in one of two ways: (1) the animal may be guided back by a series of 

 landmarks to which it has already established reactions (points de repere, 

 "visual landmarks," "familiar landmarks," etc.). Such landmarks may 

 appeal to any sense-organ possessed by the animal. If it is keen-sighted, we may 

 suppose that the landmarks would be visual; if highly sensitive to olfactory 

 stimuli, olfactory, etc. Those who support the landmark theory of homing 

 usually suppose that there is a series or chain of such stimuli so placed that 

 before one stimulus ceases to act another presents itself. It is obvious that 



*On certain phases of proximate orientation, see Lashley, page 61 of this volume. 



