It has from analogy of the female sex been rather fancifully suggested that in man there occurs about the age of fifty a critical period (_climacterium virile_) due to changes in the sex glands (Mendel[37]) or prostate (Rankin[38]); but of this there is no proof. It recalls as a kind of echo the ancient conceptions of the grand climacterics at 49 (a multiple of the number 7), 63 (7 × the magical number 9 of the Arabians), and 81, and the description in 1807 by Professor B. Waterhouse[39] of Cambridge, Mass., who in 1800 introduced Jennerian vaccination into America, of a kind of male moulting between 43 and 50 and a worse one at 63, an idea expanded into the climacteric disease imagined in 1813 by Sir Henry Holland.[40] There is indeed no doubt that after an illness, and the so-called climacteric disease admittedly seldom occurred without some previous factor such as an attack of gout, a common cold, a bout of intemperance, recent marriage, or particularly grief or bereavement, old age may come on apace. In some instances the so-called climacteric disease was perhaps really chronic renal disease, in others merely the prolonged or imperfect convalescence due to some lingering infection after an acute illness, such as influenza; and, as in the latter case recovery may occur, Holland’s contention that recovery was an argument in favour of the existence of this climacteric disease holds good only in distinguishing it from permanent senility, which indeed was the objection that he was concerned to meet. The conception of the climacteric disease is interesting historically only; and it may be agreed that apart from accidents of environment the progress of senescence in healthy men is gradual and uneventful.