Page:Popular Science Monthly Volume 5.djvu/482

466 rolling up of the single phyllate cotyledon, these adhesions must be innumerable. Otherwise there would be no stems to plants of this class. A careful analysis will always enable us to trace the original layers, and, wherever reduced to a simple leaf, to find the law invariable.

It is manifest that all these creatures live externally. The leaf is the type of all; and every metamorphosis is some modification of a leaf. Even creatures of a single cell may be regarded as diminutive leaves; and all leaves are compounds of simple cells. The point is, the true manner of organization or of life. The grand peculiarity of all of them is that the great disturber—life-destroyer and life-giver, atmospheric oxygen—must come in direct contact with each and every cell. Organisms living in this way are called plants—a term which has no scientific meaning or value, since it indicates no relation to other creatures. All other living creatures constitute but one other grand kingdom; animals, another unscientific term. Unscientific as the terms are, it is generally supposed that we know pretty well to what they apply. We understand these are the first two branches from the main root of organic life, springing from the same original germ, and expanding into two great trees, never uniting nor mingling their boughs any more. It is easy to see the correlation of these two; the true distinction between them.

The so-called plant never loses the type or plan of the original leaf, of the primitive cell. It always remains phyllate, and living, as it were, cell by cell, in external relations to the air and the sources of nutrition. The so-called animal is more complicated. It differentiates completely the points, or spots, or organs of aëration and of nutrition; devotes one part of the organism to nutrition, and another to oxygenation. This is not all. Thus far probably all cells agree. But in animals the organs and functions of nutrition, at least, are in some fold of the tegument or sarcode, so that they store away their food in a special receptacle, and carry it about. This is as perfectly true of the most elementary amoeba as of the elephant. This view of the ground of classification has been rejected by naturalists—by Dr. Carpenter among others; but this was done years ago, inconsiderately, and without the aid of recent advances in biology.

The amœba, although a mere drop of jelly, improvises a pocket, or stomach, for the reception of its food, which, for the time being, is differentiated to nutrition. The so-called plant, on the contrary, has its mesentery, as well as its apparatus for aëration, external to the organism. The animal involutes a part of its investing tegument; takes the mesentery, at least, into the inside of the body; and, in the higher orders, the lungs also.

The scientific relations of the two kingdoms are well indicated, therefore, in the terminology which classifies the one as Exothens—external livers; and the other as Endothens—internal livers.

As to their life, and the elements of organization, they are precisely