8o 



NA TURE 



\Nov. 26, 1885 



Can an Animal Count ? 



Sir John Lubbock, in his interesting paper on animal intel- 

 ligence (Nature, vol. xxxiii. pp. 46-7), virtually puts this 

 question with reference to the dog. But the question whether 

 a dog, or any other animal, can count will depend upon what 

 we mean by counting. In the ordinary and correct signification 

 of the term, counting consists in applying conventional signs to 

 objects, events, &c., as when we say "one," "two," "three," 

 to the striking of a clock. Clearly in this sense there is no 

 reason to suppose that any animal can count. But there is another 

 sense in which the term " counting " may be used — i.e. as desig- 

 nating the process of distinguishing, with respect to number, 

 between the relative contents of two or more perceptions. 

 While addres.sing an audience of 100 individuals a lecturer can 

 immediately perceive that it does not contain 1000 ; and even 

 without, in the true sense, counting them may make a tolerably 

 close guess at their number. The accuracy of such a guess will 

 depend upon two conditions. The first of these is the number 

 of units to be computed, and the second is the previous jDractice 

 he may have had in that kind of computation. Thus, every 

 man is able to tell the difference between one and two, two and 

 three, &c., up to perhaps seven and eight objects or events, 

 without resorting to the e.Npedient of marking olf each with a 

 separate sign. But somewhere about this point most persons 

 require to adopt a system of numerical notation, if they desire 

 to be accurate ; and probably no one, without either special 

 practice or some such system, could be perfectly sure whether he 

 held eleven or twelve shillings in his hand, or whether a clock 

 had just struck eleven or twelve. Indeed, it is just because of 

 the rapidly-increasing difficulty of thus computing diminishing 

 diflferences of ratio by immediate perception, that primitive man 

 first lays the foundations of arithmetic by marking off the objects 

 or events upon his fingers and toes. As already indicated, how- 

 ever, special practice makes a great difterence in tlie accuracy 

 with which such instantaneous computation can be made. 

 Several years ago Prof. Preyer, of Jena, tried some experiments 

 upon this subject, and found, if I remember correctly, that after 

 a course of special training one might acquire the power of 

 instantaneously distinguishing between twenty and twenty-one 

 dots promiscuously scattered over a piece of paper. 



Now, it is clearly only in this way that animals can be sup- 

 posed to count at all ; and, therefore, the only question is as to 

 how far they are able to take immediate cognisance of the pre- 

 cise numerical content of a perception — or, in the case of a 

 series of events, how far they are able to take similar cognisance 

 of their past perceptions. But, as Sir John Lubbock observes, 

 there is no record of any experiments having been made in this 

 direction. Houzeau (tom. ii. p. 207) says that the mules used 

 in the tramways at New Orleans are able to count five ; for they 

 have to make five journeys from one end of the tramway to the 

 other before they are released, and they make four of these 

 journeys without showing that they expect to be released, but 

 bray at the end of the fifth. If this is really a case of " count- 

 ing," in the incorrect sense of the term (and not due to observing 

 some signs of their approaching release), it is probably due to 

 their perception of a known amount of fatigue, a known duration 

 of time, or some other such measure. 



Several years ago my sister tried to teach an intelligent terrier 

 to fetch a stated number of similar little woollen balls placed in 

 a box at a distance from herself — the number stated, or ordered, 

 being purposely varied from one to six. But although she is 

 good at teaching animals, and here went to work judiciously in 

 ways which I need not wait to describe, the result, as in the 

 case given by Sir John Lubbock, was a total failure. 



My object in making these remarks is to point out that in 

 experiments of this kind the game seems scarcely worth the candle. 

 Even if it were proved that a dog could "count" up to any 

 particular number, all that we should have proved would be that 

 the dog is able to distinguish between the degrees of two or 

 more jjerceptions of a given kind ; we could not thus prove any 

 abstract conception of number on the part of the animal, such 

 as is implied on the part of the " Damara floundering hopelessly 

 in a calculation." Howsoever hopeless such floundering may be 

 if the man is really calculating — i. e. employing some system of 

 numerical signs — his operations are being conducted on a totally 

 different psychological level from those of the bitch who, in 

 surveying her litter of puppies, perceives that there is not so 

 great a mass of them as she reinembers to have perceived before. 

 Psychologically considered, the artifice of numerical notation is 

 as far above any such faculty of simple perception, as the artifice 



of alphabetical writing is above that of simple association. I 

 cannot doubt that a moment's thought would have shown Sir 

 John Lubbock how needless was his precaution — while esta- 

 blishing certain associations of ideas in a dog's mind between 

 written words on a card and the things signified— of spelling 

 the words phonetically, "so as not to trouble him by our 

 intricate spelling." 



It is a most interesting fact that a dog's attention can be so 

 far fixed upon written signs that a special association of ideas 

 admits of being established between them and the things signi- 

 fied ; but the psychological distance between establishing such a 

 special association and spelling a word is so enormous as not to 

 admit of computation. And similarly, even if my sister had 

 succeeded in teaching her terrier to fetch a stated number of 

 balls at word of command, no one could have supposed that she 

 had thus taught the animal to count, in the sense of employing 

 any .system of numerical notation : she would only have proved 

 the degree in which this animal was able to perceive, without 

 counting, the different appearances presented by this, that, or 

 the other volume of balls in a box. 



George J. Romanes 



Lodge's "Mechanics" 



Permit me to thank Prof. Tait for his kind and amusing 

 criticism of my little book. I am struck with comic horror at 

 the thought that anything in the preface can be construed 

 into a comparison between works like Thomson and Tait, 

 Clerk-Maxwell and W. K. Clifford, with such elementary 

 picture-books as Deschanel and Ganot. I do not indeed 

 share Prof. Tait's contempt for these "foreign" books; a 

 student will find in them details, about (say) barometers or air- 

 pumps, for which he may search the other works mentioned in 

 vain. I did not urge students to read Thomson and Tait, 

 because to those who can the advice is superfluous ; to those 

 who cannot it is disheartening. I did, and do, recommend 

 such junior students as we get at provincial colleges to read 

 easy works on Physics — not always because they contain a 

 profound and satisfactory statement of principles, for how few of 

 them do, but because they explain a multitude of details and 

 experimental developments with which it w.as unwise to encumber 

 a little book dealing mainly with vital principles, and aiming 

 at being, in its humble way, an introduction to the classics of 

 the science. 



My book is primarily intended as milk for babes ; and while 

 it would be cruel to tell a baby to look at the sun, it is possible 

 to direct his attention to a gas-light with some pleasure and 

 satisfaction. Oliver Lodge 



University College, Liverpool, November 13 



The Resting Position of the Oyster — A Correction 



In a late number of Nature (vol. x.i.xii. p. 597) Mr. J. T. 

 Cunningham makes the extraordinary announcement that Wood- 

 ward, Jeffrey, and Huxley were wrong in asserting that the 

 oyster rests on the left side. I am in a position to state with 

 positive certainty that it is invariably the left valve of the fry of 

 the oyster which becomes affixed to a foreign object. I have 

 examined thousands of very young adherent spat ranging in size 

 from i-90th of an inch to 2 inches in diameter, and have never 

 found an exception to this rule. Besides the positive statements 

 to the same effect made by Huxley and others, I would refer the 

 reader to a brief paper by myself entitled " On the Mode of Fixa- 

 tion of the Fry of the Oyster " {Bull. U.S. Fish Commission, vol. 

 ii. , 1S82, pp. 383-387) ; but I would caution the reader that Figs. 

 3 to 8 were reversed through an unfortunate oversight, as the apices 

 of the umbos of all the larval shells figured on p. 387 should be 

 directed to the left instead of to the right side. This blunder of 

 the artist is pointed out in the explanation to plate 75, where 

 the figures from the above-cited notice are reproduced in my 

 paper entitled " A Sketch of the Life-History of the Oyster," 

 forming Appendix II. to "A Review of the Fossil Ostreidas of 

 North America," by Charles A. White, M.D. , and Prof. Angelo 

 Ileilprin. In another paper of mine, " The Metamorphosis and 

 Post-Larval Development of the Oyster," Rep. U.S. Fish 

 Commissioner, Part 10, for 1SS2, p. 784, Fig. 2 shows the larval 

 shell, L, of the young spat in normal position, with the umbo 

 directed to the left. This figure may be compared with advan- 



