that there should be no resistance the beautiful adaptation of the whole instrument to its particular purposes; might be displayed perhaps to some extent in a Treatise on the Fins of Fishes, but is altogether unapproachable within the compass of this work.

The fish, whose Back Fin was cut off in the above experiment, was a Roach, and no fish can more manifestly shew us why he uses it, as well from the prominent manner in which he operates with it, as on account of his slow and constant motion.

The fish that I have examined with reference to their use of the Back Fin are a Roach, a Minnow, a Perch, and a Gold fish. A Perch however moves so little that he does not add much to our knowledge of the

matter.

There are no doubt other uses to which the Back Fin is applied, for nature seldom makes a thing to serve a single purpose. Thus a Perch, whose Back Fin is very spinous, erects it when he is in the act of feeding, and often suddenly at other times. The size of the Back Fin may be expected to be small in very broad fish, and large in those that are deep and otherwise insufficiently provided with the means of supporting the body; that is to say, the size and situation of the Back Fin depend on the shape and habits of the fish, and the relative situation and power of his other fins and tail, together with the nature of the waters that he inhabits.

All the fish that I have observed move the Eyes

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in three directions but not upwards. The way in which they move them however in most cases, is peculiar; they cannot move them smoothly or to any angle, but only to a certain angle and with a jerk. They can also move each eye independently of the other. Minnows, again, contract and dilate the pupil very much, but I never could detect the same faculty in other fish.

Those who make up the great body of people with whom we come into contact during our journey through the world, when we have seen them a few times under ordinary circumstances, are known and understood as well as if we saw them every day; because they are all made up of the same materials, and are altogether the creatures of those circumstances.

But with a few, the case is very different; we may see them every day, for years together, and yet never know nor understand them after all, because the mind, in such people, though it may not go much deeper, is not created out of their ordinary circumstances; from which it arises that, if we would understand such people, we must have an opportunity of seeing them on some occasion when the differences or peculiarities of their character are called forth... A very trivial circumstance will suffice to call them forth; and therefore a moment of time is enough to enable a man with a sharp eye to come at length to

know them thoroughly; a man with a sharp eye being a man who has penetration to discern the causes of human conduct, or to trace the motive of what is said or done, and therefore to discern the kind of person who says and does it.

And we shall find that it is the same with different species of animals, or with different individuals among ourselves. Thus with Horses, Cattle, Sheep, and Poultry, though a few individuals, here and there, may differ somewhat in individual propensities, yet when we have seen them under ordinary circumstances, their habits and manners are so perfectly made known to us, that if we were to live among them all our lives we should find out very little more about them; or rather should discover that they were always the same animals.

But it is not so with all species of animals that are common enough in many places; as for example with Stoats and Weasels; because, although we may see such animals numberless times, it is only on some rare occasion that we are able to see them under circumstances that cause them to develop their real characters and resources; as also in their case, because, where they are seen, they are commonly looked at as creatures to be killed, and are hotly pursued like a mad dog, until they are circumvented and put out of the way; instead of being contemplated with the eye of a Naturalist, as creatures who are endowed with mysterious attributes and unintelligible power.

I have watched Stoats and Weasels in their secret

haunts and seen their secret proceedings; and we have no wild animals who would oftener be visible if it was only possible to get a glimpse of them; for no animal is more constantly going about, and none works harder for his living than a Stoat or Weasel.

But he is secret and mysterious in all that he does; he is always darting into holes and oozing out again through other holes to which he had travelled under ground, or appears for an instant at a loophole in a hedge and is gone before we are certain as to his identity; and he is so silent as well as quick in all his motions, and cautious and continually peering about,

- though he chiefly depends on his ears as much to warn him of danger, as on his nose to find his food, for his eyes are of use to him only at the shortest distances that when we have caught a sight of him in his natural wilds we must be well acquainted with him if we would know where he is likely to appear again.

He is also as curious and inquisitive as he is quick and cautious, or seems to be so, because he cannot see well; and therefore when he hears a noise, being interested in all that may tend to his good or evil, and also cautious, and accordingly slow to decide about the meaning of a thing until he has found out what it means, he is obliged to go close to the place before he can make up his mind. From which it arises that when we have disturbed a Stoat, or Weasel, if we are careful to stand still and be quite silent, we are almost sure to see him again; particularly if we are able to

imitate the crying of a Rabbit or a Rat, when we may safely depend on seeing him, and also on his coming very near to us.

A Stoat is not by any means a fleet animal, but what he wants in speed he makes up in address; so that a dog on his own ground can rarely manage to get hold of him.

I was sitting on some logs of wood in a quiet field by the side of a quiet coppice, and had also with me a dog for a companion, who was used to my quiet way.

After I had been there some time, I saw a rabbit run out of the wood and go towards the middle of the field; he did not go far and seemed to hesitate, and, after some uncertain movements, turned and lay down or squatted in the grass. He had an unusual appearance, and from his running in that manner I was led to suspect that a Stoat was hunting him, so I kept my dog where he was, and shortly saw a Stoat come out at the same place and follow upon the scent.

But he was not then the lurking and timid creature that he is when we see him at other times, but earnest and violent, and bold and brave; he threw himself from side to side with his head up in the air, like a well broken pointer who is quartering a field, until he hit off the line in which the Rabbit had gone, when he kept it with the skill and ardour of a Bloodhound, who knew from the state of things that he was close upon his prey.