Page:The Harveian Oration,1902.djvu/41

 beneficent action in annulling pain, chloroform minimises the otherwise dangerous, or even fatal, depression that might result from severe surgical procedure.

Most, if not all, of the cardiac and vascular reflexes are capable of being elicited through the medullary centres alone, and they can be obtained with great facility, as Brodie and I have found, in decerebrate animals.

The cardiac and vascular reflexes have an especial bearing on the circulation in the brain. The cerebral circulation has many features of an exceptional character. The doctrine propounded by Monro Secundus, supported by Kellie and Abercrombie, and most ably advocated at the present day by Leonard Hill, is that, as the cranium is a closed cavity and the brain substance incompressible, the quantity of blood within the skull must practically be at all times the same—the blood flowing out of the veins to make room for that flowing in by the arteries—those conditions only being excepted in which fluid or other matter is effused or secreted by the blood-vessels, for, in such circumstances, a quantity of blood equal