Wolff and Forbes, in the preceding paper of this series of studies,1 showed that the administration of hypertonic solutions, both intravenously and intraperitoneally, is followed by diminution of the caliber of the arterioles and venules of the pia. They also found the converse, that hypotonic solutions caused dilatation of these vessels.
Their observations did not involve any study of the vessels of the brain itself. To see the changes in the pial vessels clearly, it was necessary to use relatively high magnifications and an illumination with green light, which did not permit of simultaneous observations of the color of the cortex. In the present investigation it was found, however, that color photography, under white light, gives an accurate record of the delicate flushing and paling of the cortex, with a somewhat less sharp discrimination of the changes in the pial vessels. Thus the two technics supplement each other.
KUBIE LS, HETLER DM. THE CEREBRAL CIRCULATIONIV. THE ACTION OF HYPERTONIC SOLUTIONS PART II. A STUDY OF THE CIRCULATION IN THE CORTEX BY MEANS OF COLOR PHOTOGRAPHY. Arch NeurPsych. 1928;20(4):749-755. doi:10.1001/archneurpsyc.1928.02210160088006