The capillary circulation of the brain has received little attention from investigators of cerebral physiology. Although Hill,1 in 1895, pointed out the relationship between the blood flow through the brain and its metabolism, it is only in the last few years that any quantitative studies of the blood supply to nerve tissue have been made. A comparison between the capillary bed of the brain and that of other organs is significant. Krogh2 measured the capillaries in muscle and made a plea for more quantitative studies of this sort, saying: "I believe that when taken up in earnest by competent anatomists, the field of quantitative anatomy will prove to be a rich and fruitful one. Many determinations of vascular and glandular surfaces are urgently needed as a basis for quantitative physiological work."
In a previous paper,3 I deduced from the published work of Wearn, Krogh and Craigie that