318 DR. G.J. ROMANES ON THE MENTAL [June -1, 



of fruit as payment. In this way the ape was eventually taught to 

 associate these three numbers with tlieir names. Lastly, if two 

 straws or three straws were demanded, she was taught to hold one 

 straw or two straws in her mouth until slie had picked up the 

 remaining straw, and then to hand the two straws or the three straws 

 together. This prevented any possible error arising from her 

 interpretation of vocal tones — an error which might well have arisen 

 if each straw had been asked for separately. 



As soon as the animal understood what was required, and had 

 learnt to associate these three numbers witli their names, she never 

 failed to give the number of straws asked for. Her education was 

 then extended in a similar manner from three to four, and from 

 four to five straws. Here, for reasons to be presently stated, I allowed 

 her education to terminate. But more recently one of the keepers 

 has endeavoured to advance her instruction as far as ten. The result, 

 however, is what might have been anticipated. Althougb she very 

 rarely makes any mistake in handing out one, two, three, four, or five 

 straws, according to the number asked for, and although she is 

 usually accurate in handing out as many as six or seven, when the 

 numbers eight, nine, or ten are named, the result becomes more and 

 more uncertain, so as to be suggestive of guesswork. It is evident, 

 however, that she understands the words seven, eight, nine, and ten 

 to betoken numbers higher than those below them ; and if she is 

 asked for any of these numbers (?!. e., above six), she always gives some 

 number that is above six and not more than ten ; but there is no 

 such constant accuracy displayed in handing out the exact number 

 named as is the case below six. On the whole, then, while there is 

 no doubt that this animal can accurately compute any number of 

 straws up to five, beyond five the accuracy of her computation 

 becomes progressively diminished. 



It is to be noticed that the ape exhibits some idea of multiplica- 

 tion ; for she very frequently (especially when dealing with numbers 

 above five) doubles over a long straw so as to make it present two 

 ends, and thus to appear as two straws. Any of the comparatively 

 rare errors which she now makes in dealing with numbers below 

 six are almost invariably due to her thus endeavouring to duplicate 

 her straws. In this connexion it is to be remembered that, owing 

 to the method above described (whereby the ape is required to place 

 each straw separately in her mouth until the sum asked for is com- 

 pleted), when any high number is demanded, a considerable tax is 

 imposed upon her patience ; and as her movements are deliberate 

 while her store of patience is but small, it is evident to all observers 

 that the doubling of the straws is intended to save trouble by getting 

 the sum completed with greater lapidity than is possible wheu every 

 straw is picked up separately. Of course we do not recognize these 

 doubled straws as equivalent to two straws, and therefore the persis- 

 tency with which she endeavours to palm them off as such is the 

 more noteworthy as evidence of her idea of multiplication. More- 

 over, I am disposed to think that the uncertainty which attends her 

 dealing with the numbers six and seven is more largely due to her 



