THE PROBLEMS OF CANCER 103
question of a certain limited number of cell divisions before they present the phenomena associated by many embryologists with the reduction of chromosomes. In short, the proof furnished by the researches of Farmer, Moore, and Walker, of the occurrence of divisions in cancer and sarcoma cells usually associated with the maturation of germ-cells, was the one thing lacking to establish beyond question the true nature of a malignant tumour as the pre-embryonic portion of the life-cycle, the asexual generation. While at present it would be wrong to assume that such cell divisions must of necessity occur at some time or other in all malignant tumours—for even a malignant tumour may conceivably be so reduced or retrograded as to be unable to repeat the whole cycle of the germ-cells, just as no tumour is known to form actual sperms—it is now beyond doubt that the occurrence of such divisions in certain cases proves a malignant neoplasm to be the pre-embryonic portion of the life-cycle. It is a life-cycle with the embryo omitted. Germ-cells never do arise, and never could have arisen, from somatic or embryonic cells or tissues.
The true science of the tumours, then, has its embryological basis in the facts and phenomena of identical twins, triplets, etc. The facts of normal development, as seen in identical twins, as well as in certain armadillos, many sheep, etc., demand that we should recognize that just prior to the unfolding of an embryo there are “n” divisions of germ-cells, resulting usually in one embryonic cell and a certain as yet undefined number of retrograde or rudimentary embryonic cells. Like the polar bodies of oögenesis as rudimentary gametes, these have now lost to a greater or less degree—this varying in different cases—their powers of undergoing a completely normal development. They are not to be confused with those