370 THE BIOLOGY OF THE SEASONS 



that the young mammals are sooner able to look after 

 themselves, and so on. If the golden eagle matures at 

 about ten years, and lays two eggs a year, " then a pair will 

 produce one hundred eggs in fifty years, and of these only 

 two will develop into adult birds ; and thus on an average a 

 pair of eagles will only succeed in bringing a pair of young 

 to maturity once in fifty years." For this reason, golden 

 eagles have a high degree of longevity. 



Before we pass to the striking contrast between man 

 and animals as regards growing old, let us consider for a 

 little some of the human signs of old age. What are the 

 signs of normal senescence ? 



According to one line of interpretation at least, we have 

 one of the sublimest pictures of senility in Ecclesiastes xii. 

 The mind and senses begin to be darkened, the winter of 

 life approaches with its clouds and storms ; the arms 

 the protectors of the bodily house tremble, the strong 

 legs bow, the grinders cease because they are few, the 

 apples of the eyes are darkened, the jaws munch with only 

 a dull sound, the old man is nervously weak and startled 

 even by a bird chirping, he is afraid of even hillocks, his 

 falling hair is white as the strewn almond blossoms, he 

 drags himself along with difficulty, he has no more appetite, 

 he seeks only for his home of rest, which he finds when the 

 silver cord is loosed or the golden bowl broken. 



Let us take a more modern expression. Professor 

 Humphrey had direct or indirect knowledge of the state 

 of the body in five hundred men and women of eighty years 

 of age and upwards, when, in a famous lecture, he summed up 

 as follows : 



" In the normal ' descending ' development the relative 

 proportions of the several structures and organs are pre- 

 served, while weight, force, and activity are being lowered 

 by a gradual and well adjusted diminution of material and 



