say, "I will not feed them." Ten seconds after the former signal, I would take a bit of fish to the top of the screen; after the latter signal I would not. The kitten learned in time to react to the former by climbing up, and to the latter by staying still. But its progress in learning showed that it did not learn by getting ideas of the two sounds and associating them, one with the idea and act of climbing up, the other with the idea and act of staying still. If that had been the case it would have changed suddenly from indiscriminate reactions to both signals to clear discrimination. That is, of course, what a human The cat did not. It gradually

adult would have done. climbed up, in more and more cases, at the signal that meant food, and stayed down, in more and more cases, at the signal that meant no food. This failure to form ideas of the successful acts, and so to do them directly, is characteristic of the behavior of dogs and cats throughout, and is shown by the gradualness of their learning in all save the simplest performances.

Other lines of evidence we may pass by. It is clear that the mental life of the dogs and cats is homologous only to those aspects of human mentality concerned with learning in infancy, and with the acquisition of habits by a method of trial and success in later life. Here the homology is complete. We can trace back this form of human learning nearly as far as we can the back-bone, perhaps farther.

As we go up in the vertebrate scale from the fishes, of which our fundulus was an example, to the mammals represented by our kittens and dogs, we can see a clear evolution of the animal sort of learning. The higher vertebrates can learn more things, a greater variety of things; they can form more delicate and more complex associations; they can retain the associations thus formed longer. This evolution continues through the human species, and the animal method of learning reaches its acme in man. our trades and games and accomplishments, in speech and song, we form more associations of the purely animal sort than do any of the animals, associations excelling theirs also in delicacy, com

In

plexity, and permanence. In addition we possess a life of ideas which is barely hinted at in them.

If man's psychological position in nature is apart from that of the lower animals, in general, in consequence of his ability to have ideas of all sorts and to learn by them, it becomes important to examine his mental kinship to his nearest physical relatives, the monkeys, and to ask, in particular, how far the latter represent an advance from the condition found in dogs, cats, and other mammals toward that found in man. With this aim I undertook the experiments with monkeys already mentioned.

The monkeys were tested in all the ways so far described, and in others as well. Observations were made of their methods of learning to get into and out of boxes of various sorts.

Mechan

isms were devised which, when a nail was pulled out or a button pressed, etc., etc., threw a bit of food into the cage.

An apparatus was used for exposing cards which served as signals to which the monkeys learned to respond by certain acts. Their general behavior in all sorts of ways was closely watched.

From what has been said, it will be clear that the monkeys might represent an advance along either or both of the following lines: (1) the presence, at least to some extent, of a stock of ideas influential in modifying conduct, or (2) the development of the animal method of learning by an increase in the number, delicacy, complexity, and permanence of the associations formed between situations and impulses to action.

There are in the behavior of the monkeys some signs of the first sort of advance, and one cannot feel the certainty in denying them an ideational life which he feels in the case of the dogs and cats. Yet they do not learn by seeing their fellows or human beings do things, nor from being put through the acts, thus failing to manifest two of the chief symptoms of a stock of ideas.

The second sort of advance, however, is shown by the monkeys' behavior in all sorts of ways. No. 1., for instance, learned readily to open doors held by bars, single and double, hooks, single and double, bolts, loops of wire hung over nails,

plugs, levers, etc. It was hard to put together by rough and ready carpentering a mechanism which his varied acts would not sooner or later hit upon. He learned readily the delicate discriminations involved in reacting differently to the letters T and K, to lines an inch and a half-inch long, etc. After trials with three different doors, one held by a hook, one by a bar, and one by a plug, he at once succeeded with a door held by a bar, a hook, and a plug. This triple act was one learned with some difficulty by dogs and cats. When tested after fifty to seventy days interval, in which he had no practice with the boxes, he opened them as well as ever. Moreover, the quickness and suddenness of the formation of habits by the monkeys, although they are not themselves uniform enough to furnish evidence of the existence of ideas, are beyond anything we observe in the case of dogs Whereas a kitten had over 350 trials with the signal, "I will not feed them," before it learned utterly to disregard it, the monkey just mentioned learned to disregard a diamond shaped surface of black (the other signal being a buff colored surface of identical shape) in less than a hundred trials. If, then, we think of the human mind as a storehouse of ideas, the monkeys must be set apart with the other mammals, but if we think of it as the most complex associative mechanism in the animal kingdom, the mind of the monkeys should be included with it in a common group.

and cats.

Now the human mind is both. Consequently the extent to which one admits our mental kinship with the lower animals depends upon the degree of emphasis one lays on each of these two aspects. Throughout this article I have emphasized the ideational aspect of human life in order to secure a clear picture of the animal type of mentality. But to the question, “Which aspect is the more fundamental, the more important one in mental evolution?" I should certainly reply, "The increase in the human mind in the number, delicacy, and complexity of associations of the animal sort"; for from that difference we can, I believe, derive the other.

So, though for practical purposes and for common sense, man and the lower animals are mentally far apart, the deeper student may find the human mind to be as close a relative to their minds as is his body to their bodies. And it will seem nearest of all to the mind of the primates,-his nearest physical relatives.

CHRONICLE OF THE MONTH

JOSEPH B. BISHOP, New York City.

The ratification of a new treaty with Great Britain in regard to an isthmian canal is an event of the recent past which transcends all others in importance. It marks the opening of a new chapter in the commercial and diplomatic history of this country, and removes an element of discord that for half a century has chilled the friendly relations of two nations and at times menaced their peace. It opens the way for the construction of an interoceanic highway for the commerce of the world, thus carrying into effect an enterprise that has occupied the minds of men for three hundred and fifty years. Within half a century after the discovery of America, the possibility of uniting the Atlantic and the Pacific by piercing the Central American isthmus became a subject of eager controversy. Columbus was seeking a direct route to the Indies when he discovered America, and no sooner had Spain established her colonies on American soil than she again took up the quest. Her engineers, early in the sixteenth century, made surveys at different points on the isthmus, and formulated plans which were laid first before Charles V., and afterwards before Philip II. In 1550, Antonio Galveo, a Portuguese sea captain and navigator, published a monograph on the subject. In the following year, Lopez Gomara, a Spanish historian, appealed to Philip II. to undertake the work, and in doing so discussed the relative merits of three routes,-Nicaragua, Panama, and Tehuantepec. "To a King of Spain," he said,

Copyright, 1902, by Frederick A. Richardson.