114 GROWTH OF PARTS AND ORGANS 



The four tables 68, 69, 70 and 71 which follow have been worked 

 out on the basis of body length by the use of the appropriate 

 formulas. The details touching the organs represented, as well 

 as the corresponding graphs, are to be found in the earlier para- 

 graphs of this chapter. The values for the body weights are 

 repeated in each table. 



Weights of viscera combined. Using the data in tables 68- 

 71 (72) the total weight of the viscera brain, spinal cord, both 

 eyeballs, heart, both kidneys, liver, spleen, both lungs, alimen- 

 tary tract, both testes, both ovaries, hypophysis, both supra- 

 renals, thyroid and thymus (given separately) has been entered 

 after the total body weight at each millimeter of body length 

 and for each sex. For obvious reasons the weight of the total 

 blood (see table 70) has not been included. 



For the thymus, the weight of which is most closely correlated 

 with age, the following procedure has been employed. Using 

 table 62 for the values for the body weights at given ages, the 

 relation between age, body weight and thymus weight has been 

 directly tabulated, and using these data as a basis, the values 

 of the thymus for the body weight which is assumed to be nor- 

 mal to the age have been determined as given in table 73. 

 Owing to the manner in which they have been obtained, it has 

 seemed best to give the thymus values in a separate column. 



The entries for the thymus cease after a body length of 221 mm. 

 for males and 198 mm. for females, as these mark the limit of the 

 data in table 62. But in animals of this size or larger, the value 

 for the thymus has become very small both absolutely and 

 relatively. 



Tables giving characters which depend primarily on age. 



Table 74 gives the percentage of water in the brain and in the 

 spinal cord for each sex from birth to 365 days. These values 

 have been computed by formulas (40) , (41) and (42) . The graphs 

 corresponding to these data for the males are given in chart 26. 



