Cazalis long ago originated the oft-repeated aphorism: “A man is as old as his arteries,” these vessels, by means of which the blood is distributed throughout the whole system, being of immense importance in the economy of the organism. When the connective tissue is so freely developed as to cause a hardening of the arteries, these are hampered in the exercise of their function and become very brittle. According to Demange, all the special modifications undergone by the body during the period of old age may be attributed to this atrophy of the arteries, but this theory is proved to be an exaggeration by the fact that post mortems on the aged frequently reveal the presence of little or no arterial sclerosis. It might fairly be supposed that the hardening seen in many organs of the body during the period of old age is universal, and lends greater strength to the frame. The bones, which are separated from one another in youth, become welded together in old age owing to the calcareous deposits in the joints, and the ossification of the joints between the vertebra frequently causes the backbone to assume the appearance of a continuous bone, the greater part of the cartilage having become ossified. In spite of this, and as though for the purpose of proving how physically full of contradictions is the period of old age, the human frame actually becomes lighter and the quantity of component mineral substances becomes less. This brings about a liability to fracture of the bones in old people. The fracture of the neck of the femur is a constant cause of death in the aged, as occurred for instance in the case of Virchow, one of the most distinguished medical scientists of the nineteenth century. Is science, it may be asked, in a position to state precisely what are the principal modifications which occur in the tissues of old people? At the International Congress of Medicine held at Berlin in 1890, a well-known German anatomist, Merkel,[295] attempted to reply to this question. Speaking of the tissues of old people, he tried to show that certain of these, such as the skin and the mucous membrane (the epithelial tissues), preserve their youthful characters to the end, whereas others, such as the connective tissues, display profound changes. This essay was the first attempt to form a picture of the details of senile degeneration, but it did not reach any simple, general conclusion.