We know also comparatively little in regard to the origin and destruction of the cellular elements of the blood, and can only depend on the microscopic examination of their forms and appearances in health and in many conditions of disease. These have been abundantly studied morphologically, but mainly in the more severe forms and later stages of cancer, as detailed somewhat in my former lectures. Enough was there quoted to show the continued degeneracy of the blood after a cancerous growth had acquired some progress; there has also been observed some improvement for a while after the removal of a tumor, evidencing the deleterious effect of the hormone secreted by a cancerous mass. The laboratory study of the blood from 22 of the cancer patients in the New York Skin and Cancer Hospital under my care, has been instructive as well as valuable along certain lines. In most of them it was made weekly, and often over long periods of time, and the results tabulated for easy comparison, in order to study closely the condition of the patient and the effect of remedies. No very startling revelations were made by these blood studies, they confirmed in the main the observations of others, though some interesting facts were learned from an analysis of the data. They referred to ten cases of cancer of the breast, four of the stomach, two of the uterus, one of the rectum, one of general abdominal carcinosis, and the rest in scattered locations. The lowest hemoglobin index was 35, with 2,800,000 red blood cells, in a woman aged 59 with cancer of the stomach. The next lowest hemoglobin index was 45, with which the patient, aged 53, died, with inoperable cancer of the right breast; the blood count showed 3,700,000 erythrocytes, and 10,400 white blood cells, 76 per cent of which were polynuclear. During the course of observation, covering several months, the red blood cells were once 2,100,000, but under careful treatment rose to 4,110,000 not long before death. The next lowest red cell count observed was 2,200,000, with 12,000 white blood cells, and 65 hemoglobin index, in a man aged 52, with a terrible inoperative cancer of the cheek and neck, of which he died.