We can therefore affirm, without fear of advancing too much, that the grand division of nature's productions into _Animals_, _Vegetables_, and _Minerals_, do not contain every material being; since there are some that exist which cannot be classed in this division. We have already observed, that nature passes by insensible links from the animal to the vegetable, but from the vegetable to the mineral the passage is quick, and the distance considerable; from whence the law of nature's passing by imperceptible degrees appears untrue. This made me suppose that by examining nature closely we shall discover intermediate organized beings, which without having the power of reproduction, like animals and vegetables, would nevertheless have a kind of life and motion; other beings which, without being either vegetables or animals, might possibly enter into the composition of both, and likewise other beings which would be only the assemblage of the organic molecules I have spoken of in the preceding chapters.
In the first class of these kind of beings eggs must be placed; those of hens, and other birds, are fastened to a common pedicle, and draw their nourishment and growth from the body of the animal, but when fastened to the ovary, they are not then real eggs, but only yellow globules which separate from the ovary as soon as they have attained a certain growth. Their internal organization is such that they derive nourishment from the lymph, the matrix of the hen, and by which they form the white membranes, and at last the shell. The egg therefore has a kind of life and organization, a growth, expansion, and a form which it assumes by its own powers. It does not live like an animal, nor vegetate like a plant, nor is possessed of the power of reproduction; nevertheless it grows, acts externally, and is organized. Must we not then look upon it as a being of a separate class, and which ought not to be ranked either with animal or mineral? for if it is pretended that the egg is only an animal production, destined for the nutriment of the chicken, and should be looked upon as a part of the hen; I answer, that the eggs, whether impregnated or not, will be always organized after the same mode: that impregnation only changes an almost invisible part; and that it attains its perfection and growth, as well externally as internally, whether it contains the chicken or not, and that consequently it ought to be considered as a separate being.