SUPPOSED POWERS OF COUNTING.

283 each species. How, then, does the insect know when her task is fulfilled? Not by the cell being filled, for if some be removed she does not replace them. When she has brought her complement she considers her task accomplished, whether the victims are still there or not. How, then, does she know when she has made up the number twenty-four? Perhaps it will be said that each species feels some mysterious and innate tendency to provide a certain number of victims. This would not under any circumstances be an explanation, nor is it in accordance with the facts. In the genus Eumenes the males are much smaller than the females. Now, in the hive bees, humble bees, wasps, and other insects where such a difference occurs, but where the young are directly fed, it is, of course, obvious that the quantity can be proportioned to the appetite of the grub. But in insects with the habits of Eumenes and Ammophila the case is different, because the food is stored up once for all. Now, it is evident that if a female grub was supplied with only food enough for a male, she would starve to death; while if a male grub were given enough for a female it would have too much. No such waste, however, occurs. In some mysterious manner the mother knows whether the egg will produce a male or female grub, and apportions the quantity of food accordingly. She does not change the species or size of her prey; but if the egg is male she supplies five, if female ten, victims. Does she count? Certainly this seems very like a commencement of arithmetic. At the same time, it would be very desirable to have additional evidence before we can arrive at any certain conclusion.

Considering how much has been written on instinct,

284

MR. HUGGINS'S EXPERIMENT.

it seems surprising that so little attention has been directed to this part of the subject. One would fancy that there ought to be no great difficulty in determining how far an animal can count; and whether, for instance, it could realize some very simple sum, such as that two and two make four. But when we come to consider how this is to be done, the problem ceases to appear so simple. We tried our dogs by putting a piece of bread before them, and preventing them from touching it until we had counted seven. To prevent ourselves from unintentionally giving any indication, we used a metronome (the instrument used for marking time when practising the pianoforte), and to make the beats more evident we attached a slender rod to the pendulum. It certainly seemed as if our dogs knew when the moment of permission had arrived; but their movement of taking the bread was scarcely so definite as to place the matter beyond a doubt. Moreover, dogs are so very quick in seizing any indication given them, even unintentionally, that, on the whole, the attempt was not satisfactory to my mind. I was the more discouraged from continuing the experiment in this manner by an account Mr. Huggins gave me of a very intelligent dog belonging to him. A number of cards were placed on the ground, numbered respectively 1, 2, 3, and so on up to 10. A question was then asked: the square root of 9 or 16, or such a sum as 6+55 −3. Mr. Huggins pointed consecutively to the cards, and the dog always barked when he came to the right one. Now, Mr. Huggins did not consciously give the dog any sign, yet so quick was the dog in seizing the slightest indication, that he was able to give the correct answer. "The mode of procedure is this. His master tells

5

him to sit down, and shows him a piece of cake. He is then questioned, and barks his answers. Say he is asked what is the square root of 16, or of 9; he will bark four or three times, as the case may be. Or such a sum as 6+12-3 he will always answer correctly. The piece of cake is, of course, the meed of such cleverness. It must not be supposed that in these performances any sign is consciously made by his questioner. None whatever. We explain the performance by supposing that he reads in his master's expression when he has barked rightly; certainly he never takes his eyes from his master's face." *

This observation seems to me of great interest in connection with the so-called "thought-reading." No one, I suppose, will imagine that there was in this case any "thought-reading" in the sense in which this word is generally used. Evidently "Kepler" seized upon some slight indication unintentionally given by Mr. Huggins. The observation, however, shows the great difficulty of the subject.

The experiments I have made are, I feel, very incomplete, but I have ventured to place them on record, partly in hope of receiving some suggestions, and partly in hope of inducing others with more leisure and opportunity to carry on similar observations, which I cannot but think must lead to interesting results.

* M. L. Huggins, "Kepler: a Biography."

Ants, 24, 31, 43, 56, 69, 107, 115, Bombardier beetle, 65

Apis, 26, 29, 58, 69, 70, 115, 150, Brachinus, 64, 68