In the diffuse form the change in the coats of the vessels extends throughout the greater part of the arterial system, and in some cases invades the capillaries and veins. In the senile arterio-sclerosis calcareous deposits occur, which render the vessels rigid. Where these tissue-changes involve the capillaries, there may be complete obliteration of their lumen in some places. _Treatment._—In some cases the artery appears to be closed at a point ahead of the tube and will resist the injection of fluid. Usually, however, the injection can be made without resistance. Blood should be drained from these cases so as to allow as full capillary penetration as possible. When no arterial injection can be made, open the internal jugular and several other large veins, drain blood from them and then inject fluid while the tube is within the vessel. If necessary add a complete hypodermic injection to all parts of the body excepting the face. Give the cavities full treatment. For transportation, govern yourself according to the transportation rules. =Fatty Degeneration of the Arteries.=—In the fatty degeneration of arteries the process consists in the gradual replacement of certain parts of the muscular cells by fat droplets. The fat makes its appearance as minute droplets or granules in the cells. These granules, which are characterized by their dark color, gradually increase in number and ultimately the whole of that part of the cell may be transformed. During the process the granules coalesce, and in this manner form distinct drops of fat. As the process proceeds the cell is increased in size and becomes more globular in shape. The cell wall is destroyed and the cell may thus be converted into a mass of granular fat. Ultimately the matter between the granules of fat liquify. The corpuscles break up and the fat becomes distributed in the surrounding tissues. The immediate effect of this fatty degeneration is to produce more or less softening of the fatty part, which will impair or destroy its function. In the case of the artery, the internal, middle and external coats may be affected, but the external is the one usually first attacked. The inner layer or endothelium, and the connective tissue cells in the deeper layers of the inner coat may become affected in various parts of the vessel. The process may involve a great portion of the inner coat, even the whole thickness of the intima may be destroyed. The walls of the artery may be entirely solidified, the canal being closed completely with a soft, yellowish substance as a result of the disease. The artery might appear to be a solid mass when the dissecting knife is passed through. We have seen the anterior and posterior tibial, the popliteal, radial, ulnar, the aorta arteries, and especially the arch of the aorta thus affected. Calcification may be present at many places. These cases are frequently met with in old age.