The theory which then prevailed, and remained in favour throughout nearly the whole of the eighteenth century, was commonly called at that time “the evolution theory”; it is better to describe it as “the preformation theory.”[6] Its chief point is this: There is no new formation of structures in the embryonic development of any organism, animal or plant, or even of man; there is only a growth, or unfolding, of parts which have been constructed or _pre-formed_ from all eternity, though on a very small scale and closely packed together. Hence, every living germ contains all the organs and parts of the body, in the form and arrangement they will present later, already within it, and thus the whole embryological process is merely an _evolution_ in the literal sense of the word, or an _unfolding,_ of parts that were pre-formed and folded up in it. So, for instance, we find in the hen’s egg not merely a simple cell, that divides and subdivides and forms germinal layers, and at last, after all kinds of variation and cleavage and reconstruction, brings forth the body of the chick; but there is in every egg from the first a complete chicken, with all its parts made and neatly packed. These parts are so small or so transparent that the microscope cannot detect them. In the hatching, these parts merely grow larger, and spread out in the normal way. [6] This theory is usually known as the “evolution theory” in Germany, in contradistinction to the “epigenesis theory.” But as it is the latter that is called the “evolution theory” in England, France, and Italy, and “evolution” and “epigenesis” are taken to be synonymous, it seems better to call the first the “pre-formation theory.” When this theory is consistently developed it becomes a “scatulation theory.”[7] According to its teaching, there was made in the beginning one couple or one individual of each species of animal or plant; but this one individual contained the germs of all the other individuals of the same species who should ever come to life. As the age of the earth was generally believed at that time to be fixed by the Bible at 5000 or 6000 years, it seemed possible to calculate how many individuals of each species had lived in the period, and so had been packed inside the first being that was created. The theory was consistently extended to man, and it was affirmed that our common parent Eve had had stored in her ovary the germs of all the children of men. [7] “Packing theory” would be the literal translation. Scatula is the Latin for a case or box.—Translator.