the inside of the cranium, and the _dura mater_; partly, in consequence of the small blood-vessels with which these surfaces are connected, and partly, from the close application of the fibrous structure of the membrane to the bone, and which will vary with the age of the subject, and the form of the skull; the handle of the scalpel carefully introduced will afford the best instrument for overcoming this resistance, and will not be liable to lacerate the _dura mater_, or to injure the brain. In effecting the separation, the _meningeal vessels_ frequently deluge the whole surface with blood, a circumstance that deserves attention, in as much as their plenitude marks the congestive state of the brain; it shews also that the blood is in a liquid condition, a fact to which some importance has been attached, as it is supposed to occur more particularly in cases of suffocation. The inner surface of the skull may be inspected with the view of ascertaining whether it be carious. The _dura mater_, thus brought into view, may exhibit marks of inflammation; or coagulated blood or pus may be discovered on its surface, especially in cases where external violence has been inflicted; and it is particularly worthy of notice that such an extravasation, or injury, is not necessarily under the fracture, or part of the cranium upon which the violence that produced it, had been received; on the contrary it often happens that disorganization occurs in the hemisphere opposite to that upon which the blow was struck; a phenomenon to which the term “_contre coup_” has been aptly applied.[23] The _dura mater_ may now be removed and thrown back, by dividing it all round the margin of the skull, and separating its attachment to the _crista galli_ with a pair of scissars; before we part, however, with this membrane, we should observe whether any osseous deposits,[24] or other morbid alterations are visible in its texture; for such changes are not uncommon in the _dura mater_, especially in the falx: the _tunica arachnoidea_ thus brought into view may present various morbid appearances; it may be opaque, or water may be found effused under it.[25]. The _pia mater_ often exhibits its veins turgid with blood, which indicates that some impediment had existed to the return of the circulation from the head to the heart. It is very important to distinguish between this appearance and that which is the result of the inflammation of the membrane; in this latter case, it should be remembered, that the small _arterial_ branches are the vessels gorged with blood;[26] and which are so multiplied as to form, by their numerous anastomoses, a beautiful network. In true inflammation also the membrane will be found thickened. There is still another source of fallacy with which the anatomist may have to contend in his examination of this organ, a state of vascular congestion, arising after death, from the effect of gravitation. In attending however to the position of the