HISTORICAL AND EXPERIMENTAL STUDY OF HOMING. 33 



stretch his head towards home, and mew continuously . The boat was turned round and round 

 to try to throw Tom off his bearings, but to no effect. Whether right side or left, bow or 

 stern, Tom was always on the part of the boat nearest home and straming as far as he could 

 in that direction. Fully a mile from any shore how could he tell wliich shore was which? 

 But few lights were visible and the lake is thickly wooded, and the cottages stand well back 

 among the trees. No member of the party, except the experimenter, who used the north 

 star for guidance, maintained orientation. Tom was wTapped up and held flat in the bot- 

 tom of the boat, and then released. This likewise made no difference. He would go 

 immediately to the part of the boat nearest home. Members of the party were blindfolded 

 and required to guess whether the boat was turned or allowed to stand, or whether rowed 

 in a straight line or a circle, and it was an even chance whether they guessed right or wrong. 

 No air was stirring and no odors were detectable to the human being. 



Hodge leaves the explanation in doubt, but is inclined to attribute Tom'.s 

 orientation to hearing. In support of this suggestion he cites an incident 

 connected with deer-hunting in Montana: 



WhUe lying on the top of a hill he watched a doe as she kept guard over her two fawns. 

 They were fully a half mile from where the obser\'er lay. He focused his field-glasses on the 

 group and became much interested in the alertness of the doe. "At a slight noise, occasioned 

 by my change of position [he was of course out of sight of the deer], a noise not even noticed 

 by myself, I was surprised to see the doe start, turn around, and point her ears in my direc- 

 tion. After a few minutes silence her attention was directed elsewhere, and this time I 

 made the least "ahem"; again both ears and head were directed towards me, and so in turn 

 for an hour I tried all manner of slight sounds — low whistles, snapping my fingers, tapping 

 my rifle stock, scrapmg the ground with my foot; all were followed with the precision of 

 response of the strychnized frog with the attent turning of the ears in my direction. 



If the movements of the deer were really made in response to auditory 

 stimuli, we would have to believe that the deer has an almost unlimited audi- 

 tory acuit}\ It does not seem to be quite excluded, however, that the deer 

 might have been reacting to visual stimuli, possibly through shadows, or 

 occasioned directly by the movements of the observer. Dr. Hodge, however, 

 does not profess to maintain that his experiment was a crucial one. 



Victor Franz* maintains that fish have an extraordinarily well-developed 

 sensitivity for detecting differences in hydrographic conditions. Currents are 

 detected in the water by means of the lateral-line organs, temperature through 

 warm and cold corpuscles in the skin (or through homologs) , salinity through 

 the sense of taste, depth through pressure. But Franz's paper is a resume of 

 convictions rather than a rejjort of experiments. He argues that the spa^vmng 

 migration is not actuated by sexual instincts, liut that it is an adaptive change 

 which has as its end result the obtaining of optimal developmental conditions 

 for the young. It is conditioned solely upon hydrographic phenomena. 



From the above survey of the literature it would seem impossible to get 

 any exact delimitations of the problems involved in homing. The work on 

 the homing pigeon has been carried out in too desultory a fashion and too much 

 under the influence of particular theories to afford satisfactory material for 

 hj^pothesis. Crucial experiments designed to bring out the facts as to what the 

 untrained homing pigeon can do are lacking. Until such have been made 

 speculation on the mechanism of return is useless. In so far as any conclusions 

 at all may be drawn from the experimental work on the homing pigeon, we 



*Die Laichwanderung der Fiache, Archiv fur Rasaen und Gesellschaftsbiologie, 7, 1910, pp. 

 159-168. 



