484 BIOLOGICAL PHYSICS 



" wits sharpened," and their scientific curiosity aroused to 

 the requisite degree, to enable them to undertake the 

 recondite task. 



The degrees to which the respective elements of the 

 skin and subcutaneous tissues are developed, and the pro- 

 portions in which they are admixed in infantine, adult, and 

 senile age respectively, constitute the basis on which the 

 phenomena of ageing are mainly determined, and the 

 material out of which they are evolved, as " time goes on," 

 by the operation of physiological law on anatomical elements 

 and in anatomical order. Thus, the infantine skin is, or 

 may be said to be, predominantly haemal in its vascularity, 

 the skin of adult life to be of a predominant neural vas- 

 cularity, in which the tactus eruditus is, or can be acquired, 

 and exercised in perfection, while the skin of the senile is 

 passively haemal, and retrogressive changes make manifest 

 the reversal to the haemal type, each conspicuous area of 

 haemal vascularity remaining in somewhat solitary grandeur 

 amid the disappearing remains of the neural vasculature. 

 It should be added that, amid all these vicissitudes of 

 cutaneous vascular change, the systemic lymph vasculature 

 undergoes a greater or lesser structural change also, but 

 not to the extent or in the degree that characterises either 

 the haemal or neural vasculatures, and, therefore, that it 

 has not the relative importance as an ageing factor that 

 belongs to either the haemal or the neural vasculatures, 

 and may be allowed to lapse from our further enquiries 

 into the subject, except so far as its temporary passive 

 attitude in certain pathological conditions is concerned, as, 

 for instance, in oedema and anasarca. The consistence and 

 depth of the skin and subcutaneous tissues, together with 

 the amount of anatomical subjacent packing or padding, 

 determine, to a great extent, the smoothness or the reverse 

 of the cutaneous surface, and hence, to a considerable 

 extent, "stamp" the various stages of the process of 

 ageing. The earlier periods of life, being characterised by 

 greater fulness and consistency of these tissues, are devoid 

 of the wrinkling of the later periods, and hence give to 

 them that appearance of youthfulness so pleasing to the 

 eye of the aesthetic, and so fruitful of poetic " inspiration " 

 in both sexes of the human race, and this is, no doubt, 



