134 Psychological Distinctions 



In the invertebrate animals, we have, apparently, proof of 

 the existence of this principle, in the fact of the great dis- 

 tances to which many hymenopterous insects are known to 

 range for food. A decisive experiment, however, is still 

 needed to render the inference conclusive ; and I venture to 

 suggest, to whoever may have the opportunity and inclination, 

 that of marking a number of bees from the same hive, and 

 suffering them to fly from, say, a hundred miles' distance. 

 There is hardly a doubt that they would be found to regain 

 their abode ; and it would be interesting to ascertain the 

 time they would require to do so. 



Some migratory birds are observed to resort annually to 

 the exact same winter quarters; for illustrative proof of which, 

 refer to Bewick's description of the woodcock. Other species 

 would seem to wander through the winter, of which the 

 waxvving may be cited as an example. They all, however, 

 appear to return to their former breeding haunts, where dis- 

 persion is effected, in those species which do not nidificate in 

 society, by the older individuals (which are always the first to 

 return) driving away their young of a former year; which 

 latter, however, do not commonly retire farther than they can 

 help, as I have had occasion to notice in some instances. 



The bearings of this law on the geographical distribution 

 of species do not appear to have been sufficiently taken into 

 consideration. For instance, Mr. Selby remarks, as an ex- 

 traordinary circumstance, tending to show within what abrupt 

 boundaries the natural range of particular species is confined, 

 the abundance of the white stork in Holland, and its exces- 

 sive rarity on the opposite English coast. In Holland, be it 

 remembered, it meets with encouragement ; whereas, in this 

 country, no sooner does an individual make its appearance, 

 than it is immediately shot down. Once allowed to settle, 

 it would doubtless soon colonise our fenny counties. 



Some years ago, a considerable flock of spoonbills settled 

 in a part of Aberdeenshire ; whereupon the whole neigh- 

 bourhood uprose in arms, till every bird of them was killed. 

 Here, probably, we have an instance of another phenomenon 

 in the animal world, which should not be overlooked in this 

 treatise. When a species increases numerically in any habitat 

 beyond what the latter is adequate to sustain (a circumstance 

 which, in the higher groups, can hardly happen, except in 

 those of social habits), either their ranks are mysteriously 

 thinned by what is termed epizooty, or an erratic impulse 

 (unrestrained by the localising principle we have been con- 

 sidering; instinctively prompts a portion of them to seek fresh 

 quarters. This is observed more in mammalians than in 



