Cazalis’s famous aphorism “man is as old as his arteries” is true in so far that the state of the arteries is a good index of the general condition, for they are extremely prone to suffer as the result of infection, toxaemia, and strain; strictly speaking, therefore, the state of the arteries is not so much an index of the individual’s age as of his adventures. Phlebosclerosis, analogous to arteriosclerosis, is common, and dilatation, often due to stagnation and lack of the normal _vis a tergo_, of the veins is a familiar change in the aged. The capillary area is diminished in the skin and elsewhere, but not uncommonly there are dilated venules or angiomas on the skin; the latter, commoner on the trunk and upper limbs and in men, were formerly known as “de Morgan’s spots” and were thought to accompany cancer, but the association is only due to a rough correspondence of their age incidence. _The blood_ of healthy octogenarians may not show any departure from that of the earlier periods of life as regards the number of the reds and the amount of haemoglobin (Hansen[163]), though some have described a secondary anaemia. Thus in a female centenarian Macnaughton[164] found slight secondary anaemia with a normal number of leucocytes, the differential count showing a relative lymphocytosis. The red bone marrow diminishes, its place being taken by fat cells. _The lymphoid tissues_ undergo atrophy all over the body including the leucoblastic bone marrow, but though it does not appear that the blood shows any definite change in the leucocyte count it is tempting to correlate the diminution of resistance to acute infections, such as pneumonia and erysipelas, with the atrophy of the lymphoid tissue. The alimentary canal often shows lymphoid atrophy in a high degree, but two normal Peyer’s patches were present in a man reputed to be 106 years old (G. Rolleston[165]). _The spleen_, in common with the lymphoid tissues elsewhere, shows atrophy, sometimes to an extreme degree, so that instead of the normal weight of 7 oz. it weighs a few drams only. The capsule is thrown into folds, and is somewhat opaque; from atrophy of the pulp and Malpighian corpuscles the vessels and fibrous trabeculae become prominent. _The thymus_, contrary to the general opinion that it undergoes involution long before puberty, has been found by Hammar[166] to increase in size up to puberty when involution begins, but proceeds so gradually that even in old age it is functional.