HE house-agent magniloquently dignifies it upon his circulars by the name of I prefer to call it by its proper

THE garden. name, a back yard.

Not that I deprecate a back yard. On the contrary. "O fortunati nimium sua si bona norint;" which may be freely translated as "Happy are they who possess a back yard, if they only knew it." Four times in my life I have had to endure existence in houses without back yards, and the result of that experience is, that nothing but actual compulsion will induce me to take any house that does not possess a back yard.

Of course the privileges of a back yard can be abused.

You can keep Cochin China fowls, and be proudly conscious that by paying eighteenpence for every new-laid egg and half a guinea for every chicken, you can keep your neighbours on either side of you awake from three A.M. until it is time for the milkman to make morning hideous with his yelping. You may even keep ducks and geese, which are to the loudest and most wakeful Cochin China cock what an ocarina is to a flageolet. You may set up hives and have the double pleasure of knowing that your insect pets frighten your neighbours out of their back yards, and of bursting into any of their gardens if your bees should choose to swarm there.

You may keep a goat, which will bleat continuously for sixteen hours out of the twenty-four. You may play the first four bars of "In my cottage near a wood" on a concertina for several successive weeks; you may light bonfires in order to burn your rubbish in your back yard, so that the smoke will frighten all your neighbours into the idea that their houses are on fire.

But, while a back yard may be thus misused, it is capable of better things. Among other uses it may be converted into a most effective means of teaching natural history. I will take my own specimen as an example. A more unpromising back yard can hardly be found. It slopes sharply from the house. It is just thirty-six feet in length by fifteen in width. The soil is a hard clay, which is singularly prolific in coltsfoot, and favourable to dandelion, plantain, dock, and other weeds. Grass certainly will grow in it, but

it is coarse, stiff, and patchy; and even if a roller could be got into the yard, it would have scarcely any effect on the grass.

There are several "trees" in the back yard, all aspen. There have been five; but the only one that deserved the name of tree gave up the struggle for existence long ago, and is now nothing but a decaying stump. Another perished in early childhood, and the largest survivor is only two inches and a half in diameter, three feet from the ground.

Yet by means of that back yard I could teach the outlines of zoology to boys and girls, so that they would never forget the practical lessons which they had learned. As neither the sea nor the river can be expected within the limits of sloping back yard, we cannot find fish; and on account of the barriers on all sides, reptiles cannot make way into it. But, with those exceptions, we shall in that back yard find representatives of every other class in zoology. There are Mammals, Birds, Molluscs, Spiders, Crustacea, Insects, Myriapuda, Annelida and Hydrozoa, or Infusoria, as they are popularly called. Many of these creatures display enough of their life-history to show the object for which they were created, and all are full of interest. so, although such a back yard may seem to an ordinary eye as dull as Homer's Iliad to a ploughboy, it only needs the instruction of the eye to be found as fascinating as is Homer to a scholar.

And

Suppose, then, that we try to teach a child the elements of zoology by means of the creatures which come into this back yard. I will ask the reader to place himself in the position of that child.

The first step will be to make the child understand that he has bones, and that these bones are inside the body. This can be done by feeling the knuckles, knees, shinbone, &c. Then he must learn the object of the skull, and must be told of the brain that is within it. Then he will be told of the vertebræ, and the manner in which his arms and legs are attached to them. will then have no difficulty in understanding the meaning of the word vertebrate.

He

Next he may be told that there are in the back yard some vertebrates which belong to the same class as himself—namely, the mam

malia. In my particular back yard the mammalia are at present represented by my two cats and my neighbour's dog, who has driven them into the branches of a tree, and is barking at them.

The child's attention may now be called to the fact, which probably he knows well enough but has not thought about, namely, that when the dog and the cat were born into the world one was a puppy and the other a kitten, i.e. a baby dog or cat, and was nourished by sucking milk supplied by the mother. This fact at once makes the child understand the difference between mammals and birds, and must be again noted when the birds are mentioned.

To return to the cats in the tree.

the slit has greatly widened. At midnight the pupils will be as circular as those of the dog, only very much larger in proportion to the size of the animals. This change is caused by the effect of light upon the mechanism of the eye, and it is invariable in the cats all over the world.

The Chinese have long known and utilised this phenomenon. As we all know, they are very fond of cats, both as pets and for the table. In which latter taste they are perfectly right, for jugged cat is quite as good. as jugged hare, and very few persons would discover the imposition, if one were exchanged for the other. If, then, a Chinese wishes to tell the time on a cloudy day when the sun cannot guide him, he takes up the nearest cat, looks at its eyes, and from the width of the pupil can form a very good idea of the time.

Why do they run up the tree for safety, and why does not the dog try to follow them into the branches, instead of contenting himself with futile barkings below? Here we find ourselves met by two points, the irst being that the structure of the animals is different, and the second, that the instinct coincides with the structure.

Up to a certain point their structure is almost identical, but after that point they begin to diverge.

Both are, in the wild state, carnivorous animals, and both live on prey which they procure by their own efforts. But the mode in which they do so is widely different. The dog pursues its prey in the day-time, and runs it down by fair chase. None of the cats do this, but almost invariably hunt at night. Therefore their eyes are not made like those of the dog.

When Ponto has barked himself hoarse after the cats in the tree, we will call him and make him look us in the face. The "pupils" of his honest brown eyes are quite circular, like those of the human being. Suppose that we look at them again after dusk, we shall find that they are much larger than they appeared in daylight, but that they are still circular.

Having induced Ponto to go back to his own premises and coaxed the cats from their refuge, we will examine their eyes, as we did those of the dog.

The pupil of the eye will be seen to be little more than a narrow slit. Towards dusk, if we look at pussy's eyes, we shall see that

Here then we find that the instinct and structure exactly coincide, and that the dog

Claw in its sheath.

from the head and lips, and which serve as guides when the one animal is creeping along, with its eyes fixed on its prey, or the other is making its way through very narrow passages.

In both cases the eyes are otherwise employed, and so the sense of touch is brought into play. At the root of each of the whisker-hairs there is a very sensitive nerve. When, therefore, the tips of the hairs touch any object, the animal can feel it, so that it can tell by the sense of touch whether the aperture is large enough to allow it to pass. Now we will take our fourth example of

It is also predacious, it never takes its

to run down her prey and catch it in her mouth.

Then comes the beautiful provision of nature, by which the claws are kept off the ground when the cat walks, and by which its footsteps are rendered so silent as to have passed into a proverb. Such a simple lesson as this, based upon two of our most familiar animals, will be sure to set the child thinking, and to extend a similar process of reasoning to every animal which he will see.

Yet two more mammalia, one of the earth, and the other of the air, and both nocturnal.

Go out by night into the back yard, and take an ordinary entomologist's lantern. Direct the light of the lantern on the ground, and you will be tolerably sure to see a mouse hurrying along in a desperate flight caused by the glare of the lantern. It is a more strictly nocturnal creature than the cat, and has eyes much larger in proportion to the size of the body.

The latter animal is intended to pass an existence partly diurnal and partly nocturnal. Consequently, the pupils of its eyes contract under the influence of light, and guard the optic nerve from injury. But the mouse is not intended for the glare of daylight, and so its eyes do not need the contractile power that distinguishes those of the cat. Here it may be mentioned that the foxes, which lead a partly nocturnal life, have their eyes formed on the same principle as those of the cat.

Then we may point to the fact that both the cat and the mouse possess very long whiskers, i.e. bristle-like hairs which project

prey in the daytime, and it feeds exclusively on flying insects. Therefore, in order to catch the swift-winged insects, it must be able to fly better than they can, and must be gifted with eyes that enable it to see in the dark.

In the common Bat, which comes gyrating over the back yard, twisting and shooting among the insects that are invisible to the eyes of man, but perfectly visible to those of the Bat, we have an animal which fulfils all these conditions.

see.

How it is enabled to fulfil them we shall

In the first place, the eye is of very great size, and, as the creature is not meant to hunt by day, there is no need of any contractile power like that of the cat.

In the next place, means for flying have to be supplied. This is done in a beautifully simple and effectual manner.

Suppose that we compare the hand of the pupil with the corresponding paw of the cat. There will be found the four fingers, having the nails compressed into claws, whilst the thumb is very small, and scarcely projects from the wrist. Its claw, however, is just as sharp and hooked as those of the fingers, and is useful in catching prey which might escape the claws of the fingers.

Such a structure would be useless in flight, so we find that in the Bat the four fingers, as well as the bones which form the palm of the hand, are enormously elongated.

If our fingers could be elongated in similar proportion, the middle finger would reach from our foreheads to our heels. The arm bones are elongated in the same fashion, so

out some retired spot, such as the trunk of a hollow tree, a crevice in a rock, or some old building, where it will not be disturbed.

It then hangs itself up by the hooked claws of its hind feet, wraps its wings round its body, and passes into a state of lethargy. Respiration ceases altogether, and so does digestion, while the heart only gives a feeble beat once in each second, just enough to keep the blood circulating.

Scarcely any waste of the tissues takes place, and the fat which has been stored up in the body affords sufficient nourishment to keep the creature alive, though not sensible, through the whole of the winter.

The hedgehog, squirrel, and dormouse are partially susceptible of hibernation, but the Bat is the only perfect hibernator which in habits the country. Not only does it hibernate in the winter, but it passes into this lethargy once in every day, even in the midst of summer.

As the structure, so is the instinct, or vice versa. Neither the dog, the cat, nor the mouse attempts to fly in the air, nor does the Bat try to chase its prey on the ground, or dig it out of the earth like the dog. Neither does it stalk prey like the cat, nor catch its prey with its claws. The structure and the instinct work together, and their chief object is the procural of food.