EXPERIMENTS WITH CYTOST 109 



The kitten's coat remained undeveloped and it ac- 

 quired a curiously dejected facial expression. The 

 spine assumed an inward curvature and the bones of 

 the paws did not develop properly. These malforma- 

 tions are clearly shown in the accompanying photo- 

 graphs, taken shortly before the animal's death, which 

 occurred five months after the injections of cytost 

 commenced. 



At autopsy arteriosclerosis, general atrophy, ar- 

 thritis and fibrosis of the kidney, liver, and lungs were 

 apparent. Such tissue changes as these are commonly 

 found in aged animals, and because the factor respon- 

 sible for these changes is unknown, are usually classi- 

 fied as senile changes. (See Fox, 1923.) 



Since in kitten "B" these pathological changes were 

 induced by the injection of cytost, it seems possible 

 that senescence in the metazoans may in part result 

 from the accumulation of cytost. As stated previously, 

 tissue culturists have found that cells appear to be 

 immortal if provided with adequate nourishment and 

 means for the removal of waste products. However, 

 even though the former is provided, cells in culture 

 rapidly degenerate and die if their metabolites are 

 not removed. (See Lewis, 1924.) 



While the writer has not encountered another case 

 in which senile changes were induced as rapidly as in 

 kitten "B," he has by repeated injections of cytost in 

 many cats accelerated the onset of senescent changes, 

 as shown by the high incidence of arteriosclerosis in 

 animals so treated. (See Table IX.) In such cases, this 

 results long before death in external changes such as 

 we normally associate with old age. For example, 

 cat 114 (see protocol below) showed graying of the 



