124 THE ENZYME TREATMENT OF CANCER
reply is, “A new organism, an embryo.” No such thing! At the close of cleavage, in none of the higher animals is any trace of an embryo present. Something is there, but not an embryo. I will ask the. reader to regard this developing egg from the start of cleavage as a living organism, but not an embryo.
The criterion of anything in embryology is the fate or destination of the cells. In a worm’s egg, which has cleaved five times, giving 32 cells, or in a skate’s egg, which has undergone ten divisions, resulting in 1,024 cells, there is not a single cell present which is embryonic in destiny. Nearly all the cells are predestined to form portions of an asexual foundation or larva, termed by me the “ phorozoon,” or bearing animal. This is a transient organism ; for, as a rule, its life is very brief. It has a part to play in the cycle, and, like the Moor, when it has done its appointed task, it can go. The results upon which, generally speaking, my conclusions are founded have been obtained by what my late friend and teacher—Professor George Bond Howes, Huxley’s assistant and successor—was wont to term the comparative morphological (and physiological) method. Under it there is but one mode of development for all the higher animals: in essentials the life-cycle is always similar, not only from fishes to man, but from worms and even lower forms to fishes. These” phorozoa,” or asexual generations of various marine organisms, have long been known. Often, and until a connection therewith was established, they received names distinct from those of the sexual generations. Thus, the larva, “ phorozoon,” or asexual generation of a brittle star, is still known as a Pluteus, and so on.
The late Professor N. Kleinenberg first set up (1886) the doctrine of development by substitution of organs. Under this, every organ of the larva (asexual generation)