STUDIES ON X-RAY EFFECTS : I. DESTRUCTIVE ACTION ON BLOOD CELLS

1. X-rays in large doses affect the lymphocytes before any of the other circulating cells. 2. There is a sharp fall in the total number of circulating lymphocytes, which is complete 48 hours after x-ray treatment. 3. Following the immediate decrease in the circulating lymphocytes there is a primary rise, followed by another fall, which in turn is followed by a permanent rise of these cells to normal. 4. The effect of the x-rays on different species of animals varies considerably, but in those studied, cat, monkey, guinea pig, rabbit, rat, mouse, and pony, the selective action on the lymphocytes was in all instances apparent. 5. When several animals of the same species are given the same dose of x-rays, the effect on the circulating lymphocytes seems to be quantitatively parallel, when determined by blood counts. 6. The polymorphonuclear neutrophilic leucocytes, when affected at all, increase in number immediately after the administration of the x-rays and then tend to decrease below their normal level. This decrease is followed by a return to normal many days before the lymphocytes reach their original level. 7. The other cells of the blood follow the neutrophilic curve. 8. Percentage figures, as determined by differential blood counts, do not give an accurate indication of the effect of the x-rays. It is only when these are multiplied by the total white blood count that a figure, representing the total number of cells of the series per c. mm. of blood, is obtained, which varies to the stimulus in a constant manner, the variations being practically quantitative.