_Lesions._ Blood extravasations may be found at any part of the brain: a. into the brain substance; b. into the ventricles; c. from the pia mater; d. into the arachnoid sac; e. between the skull and dura mater. It is especially common in connection with the ganglia adjoining the ventricles; the corpus striatum, optic thalamus, the corpora quadrigemini, the fornix. In other cases the crus cerebri, pons, medulla oblongata, corpus calosum. In other cases the convolutions of the cerebrum or cerebellum suffer. The amount of effusion may be limited to a few drops or it may cover an extensive area and cause considerable flattening of the brain substance. When capillary hæmorrhages are present—the size of a millet seed or a pea—Friedberger and Fröhner have usually found them multiple, but when large enough to form distinct clots they are usually single and confined to one side. If a clot, involving the brain substance, is small, it merely separates the nervous fibres, but if larger, the cerebral tissue is broken down in the mass of clot, discolored, torn and softened. If the patient has survived the first attack the clot passes through the different stages of discoloration, brown, brownish yellow, yellow, and may become fibrous forming a distinct cicatrix, with loss of brain substance. In connection with the partial absorption of the effused blood, cavities may be filled with a serous fluid (apoplectic cysts), and these may show multiple loculi. The nerve fibres which lead to an old standing lesion are usually degenerated. When effused into a ventricle, blood is less readily absorbed and tends to remain as a flattened discolored layer. Extravasation between the dura mater and the cranium is probably always the result of direct mechanical violence.