_The symptoms of compression_--a full, strong, and often irregular or slow pulse; normal heat of surface; muscular relaxation; dilatation, contraction, or inequality of the pupils; stertorous breathing, and paralysis--are not unfrequently retarded, and this consideration should render the opinion very guarded. Bryant records a case (_Surgery_, vol. i. p. 216) in which a man was thrown out of a gig on to his head. After a short period of insensibility he walked for half an hour, and then gradually again became insensible, and ultimately died. A large clot was found over the left cerebral hemisphere, the blood evidently having flowed from the middle meningeal artery. The short period of insensibility probably arrested the flow of blood from the artery, which recurred on the sufferer walking. The structural form of the cranium may have much to do with the danger to be expected from blows--some skulls being thinner than others--and in a few rare instances the fontanelles may not have become ossified during life. The possibility of an unhealthy condition--atheroma--of the arteries of the brain, or of disease of the heart, must be taken into consideration before venturing an opinion as to the tendency or ultimate cause of death. It may be stated that the patient died of apoplexy. Apoplexy is a disease of old age, and seldom occurs in the young, although it is just possible it _might_ occur. The arteries should, in every case, be examined for the presence or absence of disease. When violence is used, the effusion of blood is, as a general rule, on _the surface_ of the brain; but two cases are given by Dr. Abercrombie of spontaneous bursting of a blood-vessel within the head, followed by effusion of blood _upon the surface_ of the brain. “An external injury, coexisting with an extravasation of blood into the cerebral substance, does not necessarily imply cause and effect. The previous condition of the brain, or the outpouring of blood from diseased vessels, may, in fact, have been the cause of the accident” (Hewett). When, however, blood is found effused on the surface of the brain, especially between the dura mater and the skull, either beneath or opposite to an external wound, we may reasonably infer that the hæmorrhage is due to a direct blow. Hæmorrhage so severe as to produce dangerous pressure on the brain, as a rule, comes from a rupture of the middle meningeal artery.