144 THE ENZYME TREATMENT OF CANCER
Like my fellow-workers, I had been taught to regard the development of any of the higher animals as “direct”; that is to say, from the fertilized egg a new sexual organism, a worm or a fish, a bird or a man, arose directly. From the tissues or soma of this sexual organism new reproductive products, eggs or sperms, sprang. In this way the simple cycle of “egg-sexual organism, egg-sexual organism” repeated itself ad infinitum. Under this, still generally accepted, conception of development, the germ-cells were somatic in origin, and the gradual building up (epigenesis) of a new sexual organism happened directly, when such an egg had been fertilized. Such, briefly, was the simple embryological creed which my teachers, Mimes Marshall, Huxley, and Carl Semper, taught. During some eight or ten of the early years of my original work this was my embryological faith, if an investigator may have any scientific creed.
Epigenesis, direct development, and a somatic origin of germ-cells, have now long been associated with another embryological dogma, the recapitulation theory, according to which any higher animal “climbs its own genealogical tree in the course of its development.” To what lengths and depths of scientific error this latter doctrine can lead, see the fifth revised edition of Haeckel’s “Evolution of Man.”
My embryological faith was perfectly orthodox when, on June 14, 1888, I left the shores of Black Lake, New York, with an extensive assortment of preserved material of fish development. One of the earliest finds made after the return to the Anatomical Institute of the University of Freiburg in Breisgau was of the existence of two distinct and separate nervous systems in the life history of the bill-fish, Lepidosteus osseus. About a year later the like find of a twofold nervous apparatus was