lo NATURAL SCIENCE. July, 



did not imply that in " counting " the ape employed any system of 

 notation. "We know," said he, "from our own experience, that 

 there is counting and counting, /.<?., distinguishing between low 

 numbers by directly appreciating the difference between two quantities 

 of sensuous perc eption, and distinguishing between numbers of any 

 amount by markin g each perception with a separate sign." In the 

 case of some persons, he went on to say, the former method of 

 perception could reach so far as the number twenty. It was this 

 method that he imagined the ape to exhibit, and as the perceptions 

 of such an animal are naturally less proficient than those of man, it 

 was natural that above six or seven vagueness should begin, while, 

 at least, it was perceived definitely the number was greater than 

 those correctly interpreted. 



Professor Romanes went on to attempt to make Sally associate 

 colours with their names, but although Sally could distinguish 

 between white and coloured straws, she could not be taught to dis- 

 tinguish between any of the colours. Hence he came to the remark- 

 able conclusion that Sally was colour-blind, although of course he had 

 no means of deciding whether her colour-blindness were only an 

 individual defect. 



The Bird's Foot. 



In Mr. Finn's interesting paper on the bird's foot, published in our 

 last number (Natural Science, vol. iv., p. 453), the Avriter assumes, 

 and most ornithologists would agree, that the typical number of digits 

 in the bird's foot is four. In support of this he refers to Forbes's 

 discovery of the rudiment of a hallux in three-toed birds like the 

 albatross. But he did not mention an important piece of evidence 

 discovered, or at least noted, by Garrod, and pointing in the same 

 direction. The chief muscle of the hallux is a flexing muscle named 

 the Jlexor longtis hallncis. In all cases where the hallux is absent, this 

 muscle still persists with a well-developed fleshy belly and a separate 

 tendon, the latter uniting with the deep flexor tendon of the other 

 toes. This, certainly, is strong evidence, were more evidence wanted 

 in favour of three-toed birds being derived from a four-toed stock. 

 But viewed merely as a rudimentary organ, it is not so interesting as 

 at first appears ; for in the great majority of birds, and in all near 

 allies of three-toed birds, the tendon of the flexor of the great toe 

 is connected by a tendinous slip with the common deep tendon of the 

 other toes. So it must be inferred that the flexor longus hallncis of 

 three-toed birds remains, not as a mere rudiment, but because it is 

 functional, as an accessory to the flexor of the other toes. A three- 

 toed passerine bird would be interesting, because in passerines 

 there is no connection between the flexor of the great toe and the 

 common flexor of the other toes. But there is no three-toed 

 passerine. 



