OLD AGE AND DEATH 365 



posing that the impression of old age which we get from the 

 majority of our aged fellow-beings is very different from 

 what we should have inferred from an impartial survey of 

 animal life. 



Perhaps we may recognise three grades : 



a. In many human beings, in not a few domesticated 

 animals, e.g. horse, dog, cat, and in some semi-domesticated 

 animals, notably bees, and possibly in some wild animals, 

 the close of life is marked by senility. The organism is no 

 longer in full possession of its faculties ; more than that, 

 some function or other notably that of the nervous and 

 sensory systems has gone out of gear. Intelligence has 

 waned, instincts have ceased to ring true, unified control is 

 lost, the senses are dimmed and dulled, even locomotion 

 becomes impossible, the life is reduced to an existence 

 an existence which could not be prolonged except under 

 artificial conditions comparable to those of an incubator for 

 premature infants. 



b. In a minority of civilised human beings, in some 

 domesticated animals, and in a few wild animals, the 

 decline of life is marked by senescence. Growth has long 

 since stopped, and decrease in weight and stature has been 

 going on ; there is a general shrinkage, of brain and spinal 

 cord, of spleen, lymphatic glands, and kidneys ; the gonads 

 have ceased to be active; there is narrowing or even 

 obliteration of capillaries ; the bones become thinner, 

 weaker, and of course lighter ; and the corresponding 

 functions are slackened in each case in adjustment to the 

 weakening of the bodily engine. A slight shrinkage of 

 articular cartilages, a slight weakening of dorsal muscles, 

 brings about the normal stoop. A slight atrophy brings 

 about the normal grey hairs which in this category may 

 be a crown of glory. 



c. For many animals it must be said that they reach 



