SENESCENCE, DECADENCE, AND DEATH 417 



ally characterized by loss of the cellular tissues and 

 increase of the fibrillar tissues and is accompanied by 

 diminished functional activity of all the parts involved. 



The heart is usually small, its muscle brown and tough, 

 and the subepicardial tissue either abnormally fatty or 

 quite devoid of adipose tissue. The muscle cells are 

 usually excessively pigmented. 



' The lungs usually show more or less widespread emphy- 

 sema. This probably depends upon the loss of the 

 elastic tissue and the permanent overdistention of the 

 air vesicles in consequence. The changes usually occur 

 first at the sharp anterior edges and apices of the lungs, 

 but may be universal. 



The stomach may be quite small, the glandular tubules 

 diminished in number, the muscle thinned, and the 

 fibrillar tissue increased. The loss of the glandular 

 tissue impoverishes the enzymic content of the gastric 

 juice as well as diminishes its quantity; the disturbance 

 of the muscular tissue weakens the peristaltic action, and 

 not infrequently the muscle yields to the distention of 

 gaseous contents, when fermentative changes occur 

 through deficiency of the gastric juice. 



The intestinal walls are thinned, and many of the rugae 

 of the jejunum and upper ileum obliterated. The colon 

 may be contracted and thinned or may be dilated and 

 still more thinned. 



The liver usually shows brown atrophy. It is small 

 in size, pigmented, and indurated. The quantity of bile 

 is diminished, and the urea forming and glycolytic func- 

 tions disturbed. 



The pancreas usually shows more or less atrophy of the 

 secreting structure, increase of the interstitial tissue, and 

 atrophy of the bodies of Langerhans. These bodies are 

 not infrequently the seat of hyaline degeneration. 



The kidneys show more or less atrophy of the paren- 

 chyma and increase of the interstitial tissue, and in 

 addition commonly show localized atrophic areas ref- 

 erable to changes in the blood vessels. By comparing 

 27 



