FACULTY OF NUMERATION. 453 



which they were imprisoned. The magpie can count to four, 

 but no further. If four hunters hide themselves before her 

 eyes, and three of them go away, she knows that one is 

 still there, and is on her guard. But if .... there are five 

 .... and four go away, she tliinks that all are gone, and 

 becomes careless ' (Biichner). Such assertions, however, require 

 confirmation. Meanwhile they furnish useful hints for man's 

 experiments. Bees destroy excess of eggs laid by the queen 

 (Figuier). Apes attack a solitary man, or one or two men 

 together, but do not venture to approach a large party 

 (Munzinger) ; and there are probably many other animals 

 that, in war or otherwise, correctly estimate the numerical 

 force or strength of the adversary, and act accordingly. 



Instances of calculation of numbers have been given in 

 the carrion crow or other crows (' Percy Anecdotes ') . Hou- 

 zeau, Leroy, Combe, Vimont, and other authors think it 

 indubitable that the horse and mule, as well as the dog, 

 crow, and magpie, or other animals, possess notions or 

 appreciation of number up to a certain point limited, but 

 still decided. Watson speaks and I doubt not correctly 

 of the dog and other animals being puzzled, or having puz- 

 zles, in their mental arithmetic. 



Wallace comments on the difficulty of proof in the various 

 experiments that have been made to determine the point 

 whether animals can estimate numbers. There can be no 

 doubt that further experiment is desirable, in so far as it 

 cannot be said that the nature and extent of the knowledge 

 of numbers possessed by various animals are yet thoroughly 

 understood, or have been satisfactorily demonstrated. There 

 may be a perception of number in the case of dogs that can 

 distinguish playing cards (Low). The proper management 

 of sheep by the collie apparently implies a knowledge of 

 numbers (Watson). There is probably some estimate of 

 numbers, and of their united power, in the deer at bay in 

 presence of a pack of hounds (Low). Dogs that travel by 

 railway, and get out at the proper stations, probably count 

 the number of previous stoppages, though no doubt they may 

 also, or rather, have been guided by their observation of the 

 persons or things to be met with at a particular station, and 

 not at certain others. 



