other part; and it has also cells, through which moisture and other nutriment circulate. Trees breathe through their leaves, and also gather some nourishment through them; and light and heat are as necessary to trees as they are to animals. If you keep a tree constantly stripped of its leaves, it will die, as surely as a man will if his lungs are so filled or so impaired that he cannot get oxygen to keep up the vital fires.

With man life means action. We speak, and justly too, of a man of no energy as a lifeless character; for he does not show qualities that we have a right to look for in a being endowed with life. Even a lazy man will speak slightingly of another lazy man.

Again, observe the similarity of physical structure in man and birds and quadrupeds: how the fore legs of quadrupeds and the wings of birds correspond to the arms of

men.

Yet in some parts of anatomical structure there is a wide difference between birds and men, especially in the position and shape of their lungs, and in the construction of their bones. Bones of birds are more hollow, and thus are made as light as possible for the strength required.

Their breathing-apparatus is more generally distributed throughout the body than in men or quadrupeds. A considerable portion of the bird's lungs is near the outside, and directly under the wings; hence a pressure under the wings of a bird on each side of the body will stop its breath, and death will generally ensue within one minute.

But, unlike men, birds can breathe through the hollows in their bones.

H. L. Fairchild, in "Popular Science Monthly" for April, 1882, says: "Except in water-birds, the hollow bones also contain air, and by their connection with the lungs respiration

BIRDS AND QUADRUPEDS.

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can be continued through an opening in the arm or thigh bone, although the windpipe may be tied."

I will now mention some curious phenomena connected with the development of life through a mixture of races:

One of the strangest characteristics of living things appears in what are called hybrids. These hybrids may be either animal or vegetable. They are the progeny of what appear to be two different species of plants or animals. I say appear to be different species, for I do not believe that radically different species can interbreed. Hybrids do not interbreed between themselves.

The offspring of the ass and the mare is called a mule. The horse will also interbreed with the zebra and the quagga. But horses, asses, quaggas, and zebras belong to different branches of the same family. Progeny from the intermixture of either of these are infertile among or between themselves, though they sometimes interbreed with the original stock.

The most singular trait of the cross between the horse and the ass is the difference between the mule and the hinny; the mule being the offspring of a jackass and a mare, and the hinny the offspring of a stallion and a she-ass. Now one would naturally suppose that the offspring of a she-ass and a stallion, and a he-ass and a mare, would be alike; but they are not the mule has the head, ears, and tail of the ass, and the body of a horse, but brays like an ass; while the hinny has the head, ears, and tail of a horse, and the body of an ass, but neighs like a horse; - so strangely different in hybrids are the qualities transmitted by the male and female parents.

The dog and the fox will interbreed, but their offspring are infertile with each other, though they may interbreed with

the parent stocks. The wolf and the dog, being of a nearer relationship, will interbreed, and their offspring are fertile, and rear a race of wolf-dogs.

This ability to propagate a race easily, in a great measure indicates the nearness of the relationship between races which seem to be different from each other.

SIMILARITIES IN ANIMALS.

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CHAPTER II.

SIMILARITIES IN LIVING CREATURES.

I WISH now to call attention to certain similarities, both physiological and instinctive, which pertain to nearly every class of animals, and also to the harmonious and unvarying action of the laws of nature in connection with all animated existences.

General rules apply to many characteristics of nearly every variety of living beings. The brain, stomach, heart, liver, how very similar their operations in different animals! But the heart and stomach in different orders of animals are very differently constructed.

Hunter, in his classification of animals, places, first, "mammalia and birds; having a heart with four cavities. Second, reptilia and amphibia; having a heart with three cavities. Third, fishes and mollusks (pars); having a heart with two cavities. Fourth, articulated animals; having a heart with one cavity. Fifth, medusæ; having the heart and stomach identical."

Notwithstanding these radical differences of construction the circulation of the vital fluids and the action of the vital organs have a wonderful similarity.

How strangely alike are men and animals in their affections and in their anger! What strange variations of form and habits, and yet what similarity of tastes! Brutes appear to have their seasons of hilarity, depression, and even Borrow. How piteous the moans of a dog that has lost his

master; how joyous at meeting an old acquaintance; how like, in some respects, a playful child and a playful kitten! Each will cry from a sense of loneliness, and each likes to be caressed.

How like in their industry are active human beings and bees! Each improves the time in active labor. Each has a disposition to accumulate against the time of need. Bees, like men, when they have accumulated property are disposed to keep and defend it. What a remarkable instinct (or shall I call it intelligence?) bees show in the construction of their comb, the house for their young, and the storehouse of their food! The mathematical proportions of these houses are as correct as those in any human habitation. Their hexagonal shape, and pyramidal bases placed as they are, make the strongest possible structure considering the amount of material used.

It has been stated that the bee is so made physically that it could not make its comb in any other shape; but I do not believe this statement, for I think the contrary can be shown. Obstructions have been purposely placed where bees would like to build their comb; and, to avoid these obstructions, on the one side they have built their cells larger externally than at the bottom of these cells; but on the other side they made the orifices of the cells smaller than the cells were at the bottom, and thus built the faces of the comb on a regular curve instead of straight, but still kept regular mathematical proportions. This seems to show intelligence of no mean order. But suppose the previous statement, that the bees' physical construction is such that they can build their comb in only one way, were true; then what intelligence so constructed the bees themselves that they can