Man

breathe through lungs; but they differ from all other Vertebrates in their mode of reproduction, bringing forth living young, which they nurse with milk. Even in the lowest members of this highest group of the Vertebrates, at the head of which stands Man himself, looking heavenward it is true, but nevertheless rooted deeply in the Animal Kingdom, we have the dawning of those family relations, those intimate ties between parents and children, on which the whole social organization of the human race is based. is the crowning work of God on earth; but though so nobly endowed, we must not forget that we are the lofty children of a race whose lowest forms lie prostrate within the water, having no higher aspiration than the desire for food; and we cannot understand the possible degradation and moral wretchedness of Man, without knowing that his physical nature is rooted in all the material characteristics that belong to his type and link him even with the Fish. The moral and intellectual gifts that distinguish him from them are his to use or to abuse; he may, if he will, abjure his better nature and be Vertebrate more than Man. He may sink as low as the lowest of his type, or he may rise to a spiritual height that will make that which distinguishes him from the rest far more the controlling element of his being than that which unites him. with them.

CHAPTER V.

DIFFERENT VIEWS RESPECTING ORDERS.

IT is in the search after the true boundaries and characteristics of orders that we may expect the greatest advance by the naturalists of the present day; and yet there is now much discrepancy among them, some mistaking orders for classes, others raising families to the dignity of orders. This want of agreement in their results is not strange, however; for the recognition of orders is indeed exceedingly difficult. If they are, as I have defined them, groups in Nature founded upon a greater or less complication of structure, they must, of course, form a regular gradation within the limits of their class, since comparative perfection implies comparative rank, and a correct estimate of these degrees of complication requires an intimate and extensive knowledge of structure throughout the class. There would seem to be an arbitrary element here, that of our individual appreciation of structural character. If one man holds a certain kind of structural characters superior to another,

he will establish the rank of the order upon that feature, while some other naturalist, appreciating a different point of the structure more highly, will make that the test character of the group. Let us see whether we can eliminate this arbitrary element in our estimate of these groups, and find any mode of determining orders that shall be unquestionable, and give us results as positive as a chemical analysis according to quantitative elements. I believe that there are such absolute tests of structural relations. It is my conviction, that orders, like all the other groups of the Animal Kingdom, have a positive existence in Nature with definite limits; that no arbitrary element should enter into any part of our classifications; and that we have already the key by which to solve this question about orders.

To illustrate this statement, I must return to the class of Insects. We have seen that they are divided into three orders: the long cylindrical Centipedes, with the body divided throughout in uniform rings, like the worms; the Spiders, with the body divided into two regions; and the Winged Insects, with head, chest, and hind body distinct from each other, forming three separate regions. In the first group, the Centipedes, the nervous system is scattered through the whole body, as in the Worms; in the Spiders it is concentrated in two nervous swellings, as in Crusta

cea, the front one being the largest; and in the Insects there are three nervous centres, the largest in the head, a smaller one in the chest, and the smallest in the hind body. Now according to this greater or less individualization of parts, with the corresponding localization of the nervous centres, naturalists have established the relative rank of these three groups, placing Centipedes lowest, Spiders next, and Winged Insects highest. But naturalists may, and indeed they actually do, differ as to this estimation of the anatomical structure, for the Spiders are placed above Insects by some naturalists, and many even consider them a distinct class. Have we, then, any means of testing its truth to Nature? Let us look at the development of these animals, taking the highest order as an illustration, that we may have the whole succession of changes.

All know the story of the Butterfly with its three lives, as Caterpillar, Chrysalis, and Winged Insect. I speak of its three lives, but we must not forget that they make after all but one life, and that the Caterpillar is as truly the same being with the future Butterfly, as the child is the same being with the future man. The old significance of the word metamorphosis-the fabled transformation of one individual into another, in which so much of the imagination and poetical culture of the ancients found expression - still

clings to us; and where the different phases of the same life assume such different external forms, we are apt to overlook the fact that it is one single continuous life. To a naturalist, metamorphosis is simply growth; and in that sense the different stages of development in animals that undergo their successive changes within the egg are as much metamorphoses as the successive phases of life in those animals that complete their development after they are hatched.

But to return to our Butterfly. In its most imperfect, earliest condition, it is Worm-like, the body consisting of thirteen uniform rings; but when it has completed this stage of existence, it passes into the Chrysalis state, during which the body has two regions, the front rings being soldered together to form the head and chest, while the hind joints remain distinct; and it is only when it bursts from its Chrysalis envelope, as a complete Winged Insect, that it has three distinct regions of the body. Do not the different periods of growth in this highest order explain the relation of all the orders to each other? The earliest condition of an animal cannot be its highest condition, it does not pass from a more perfect to a less perfect state of existence. The history of its growth is, on the contrary, the history of its progress in development; and therefore, when we find that the first stage of growth in the