The capillary or circulatory motion of the blood cells, after the blood has been drawn, is comparatively slow at best; but the amœboid movement of the white cells and the changes taking place in the nuclei are complicated, and often hard to intelligently watch in the field. Many of these changes occurring in the white cells are certain to escape attention, but all of them will be clearly recorded on the rapidly moving sensitive film. These motions in the white cells, though they are as yet imperfectly understood, are full of meaning to the physiologist and pathologist. The offices that the blood performs in the body are believed to be due mainly to the action of the white cells. Certainly, the character of their amœboid action is one of the surest indications of health or disease.
But with the micromotoscope it need no longer be impossible to photograph the blood in actual circulation. With a better light the cells may be seen in the thin tissue of the ear or the web of the fingers. They have often been examined in the peritoneum during an operation, and Dr. Watkins himself has made a close study of them in the web feet of some birds and the tails of fishes.
Unfortunately, the [illustration] of blood here reproduced does not show the white cells. They stuck to the glass, while the red cells, it will be perceived, retain something of their motion, continuing to flow across the field for half an hour after the blood was drawn.
MOVEMENT OF BLOOD CORPUSCLES SHOWN BY THE MICROMOTOSCOPE.