28 



HELEN DEAN KING 



TABLE 13 



Showing the increase in the iveight of the body with age for 156 male and 169 female 

 rats belonging in the seventh to the fifteenth generations of the two series {A, B). 

 A combination of the data in table 11 and in table 12 



females reach this point at an earher age than do the males. 

 The records for these inbred rats show that in many cases the 

 maximum body weight in both sexes came when the animals 

 were seven or eight months of age, at which time they were at 

 the height of their reproductive activity (King, '16), and then 

 gradually decreased; other rats increased steadily in body 

 weight until they were sixteen or even eighteen months old. 

 Autopsies made on a considerable number of unusually large 

 rats indicate that the later weight increase is chiefly an accu- 

 mulation of adipose tissue and is not, therefore, to be consid- 

 ered as true growth. 



Under the very favorable climatic conditions of California, 

 Slonaker ('12 a) found that the albino rat reaches its maximum 

 body weight, as a rule, by the age of fifteen months. In one 



