86 BIOLOGY 



matter how that old age is brought about, we must try 

 to discover what signs may be regarded as indications 

 of old age, and how they contribute to the final result, 

 death. 



With increasing old age we find changes in the body 

 that are usually called atrophy. This atrophy occurs 

 in all the tissues and organs, and is usually accompanied 

 by loss of the cellular tissues and increase in the fibrillar, 

 and also by a decrease in the activity of all the 

 parts. 



In the old we may note some loss of memory, less 

 readiness in grasping new facts and in pursuing new 

 lines of thought. There is often also a marked tendency 

 to remember old and far-off things, a token of the char- 

 acteristic loss of the old. 



If we turn to the facts that an examination of the 

 body reveals we see everywhere this atrophy of the parts, 

 faintly indicated in one organ, more strongly marked 

 in another. Many parts of the skeleton are in youth 

 cartilaginous, but in the old most of these parts are 

 replaced by bone, and though this displacement by bone 

 indicates an advance in structure, physiologically it is 

 far from advantageous, as it represents a loss in elas- 

 ticity. The change in the structure of the bones them- 

 selves may be regarded as an advance in structure, but 

 again it is disadvantageous, as it marks an increase in 

 fragility. 



In the digestive organs the stomach may be small ; 

 the minute glands in the walls are usually fewer in 

 number and consequently less efficient than in the 



