As all cell life and proliferation of tissue depends on the activity of the cell nuclei, much attention has been paid to the changes found in them and the behavior of the centrosomes and chromosomes, all of which is too technical for us to consider here: suffice to say, however, that several observers have demonstrated heterotypic mitosis in malignant tumors, and that histologic examination confirms what other judgment has indicated, namely, that the cancer cell differs from a normal tissue cell mainly in its aberrant action under some stimulus, probably derived from the animal fluids by which it is surrounded. Thus we come back to our original proposition, for these fluids are, of course, but a reflection of the nutrition of the body or diet, as modified by the action of the various organs, including the internal secretions; all this is influenced again by the action of the nervous system. It is difficult to produce definite proof in regard to the influence of nervous and mental strain and shock in the production of cancer, but careful observers have long claimed that there is such an influence, and from what I have seen I am firmly convinced that in some way these conditions often do so disturb the metabolism, or otherwise operate, in such a manner that cancer results. The influence of the mind upon the body is unquestionable, as has been so fully illustrated by Tuke, and from what I have observed I cannot doubt but that the mental depression common in those with the beginning of a process which they fear might result in active cancer, has much to do with accelerating its growth; whereas, on the other hand, the hopefulness which can arise with the attempt to change the diseased process by diet and proper medication, has much to do with the favorable results which may follow in suitable cases. In the same way the constant fear of recurrence after operative removal can have its share in inducing and perpetuating the metabolic error which excites the tissues to renewed cancerous action. I know that some of you will think that this is fanciful theorizing, but many a scientific fact, in many branches of science, has been worked out from a theory which at first has seemed fanciful. We will now consider some of the data which have been recorded in regard to the relation of the secretions and excretions of the body to cancer, including the internal secretions.