io AGE, GROWTH, AND DEATH 



thoughts, assimilating new ideas, and in adapting him- 

 self to unaccustomed situations. All this betokens 

 again the characteristic loss of the old. And as we 

 turn now from these outward investigations to those 

 which the anatomist opens up to us, we learn that in 

 the interior of the body, and in every organ thereof, 

 the species of change which I have referred to as 

 characteristic of the very old is going on and has be- 

 come in each part well marked. 1 Let us first examine 

 the skeleton. In youth many parts of the skeleton 

 are soft and flexible, like the gristles and cartilages 

 which join the ribs to the breastbone, but in the old 

 man these are largely replaced by bone. Bone repre- 

 sents an advance in organisation, in structure, as we 

 say, over the cartilage. The old man has in that 

 respect progressed beyond the youthful stage ; but 

 that progress represents not a favourable change ; the 

 alteration in structure from elastic cartilage to rigid 

 bone is physiologically disadvantageous, so that 

 though the man has progressed in the organisation 

 or anatomy of his body, he has really thereby rather 

 lost than gained ground. Indeed in the skeleton this 

 principle of loss is already revealing itself. 3 In the 

 interior of the bones of the arms, of the legs, we find 



1 Especially valuable are the data concerning men and women of over eighty 

 years collated by Sir George M. Humphry, in his book, Old Age, published at 

 Cambridge (England) by Macmillan & Bowles in 1889. 



2 The senile alterations in the jaw of man have been studied by Josef Kieffer, 

 (" Beitrage zur Kenntniss der Veranderungen am Unterkiefer und Kiefergelenk 

 des Menschen durch Alter und Zahnverlust," Zeitschr, fur Morphol. u. An- 

 thropol., xi, 1-82, Taf. i-iv, 1907). An important paper, offering good illus- 

 trations of the general principles described in the course of the present lecture. 



