“—The sixth age shifts Into the lean and slippered pantaloon;” The skin also wrinkles, particularly in the forehead and face; the hair turns grey, and afterwards white; all the senses lose their acuteness, the heart and arterial system are diminished in force; while the venous system is in a state of plethora; and hence this stage of life is exposed to diseases of a peculiar cast: the blood-vessels are also liable to ossific depositions, from which apoplexy, and various affections of the heart and other organs, arise; the faculty of reproducing the species ceases long before the natural termination of his existence, although the period at which his organs fail is more precarious and less definite than that at which they commenced their functions. Woman, in relation to her powers of propagation, may be said to anticipate the male sex in her advancement to old age; at the period of forty-five or fifty, the menstrual discharge ceases, and a change is produced in the system, called the _turn of life_, which renders women at this age subject to many diseases to which a great number fall victims; but when this dangerous time has passed, their life is even more secure, and a probability exists of its being protracted beyond that of a man of equal age; and although the breasts become flaccid, the fleshy contour of the body diminishes, and the skin forms wrinkles, yet her mental powers retain their full vigour for a considerable period, and her decline into the vale of years is distinguished by a steady cheerfulness which contributes, in no small degree, to divest the path of its thorns, if not to prolong its duration. DECREPITUDO—_Advanced Age_. At length the limbs fail under the burthen which for so many years they had sustained with ease; the exterior muscles gradually return to that state of debility in which they were during infancy, and being unable to sustain a continued state of contraction, relieve themselves by alternate intervals of relaxation, from which arise the tremors[285] so characteristic of old persons; upon the same principle is to be explained the _Vacillatio Senilis_, (see-saw) for by these motions the muscles which preserve the perpendicularity of the body, are alternately quiescent, and exerted; and are thus less liable to fatigue or exhaustion.[286] The teeth having successively dropped out of their sockets, the alveolar processes are absorbed, and the projection of the lower beyond the upper jaw, imparts a very peculiar physiognomy to the countenance. “Last scene of all, That ends this strange eventful history, Is second childishness, and mere oblivion, Sans teeth, sans eyes, sans taste, sans everything.” 2. OF IMPOTENCE AND STERILITY. 1. _IMPOTENCE._