1912.] The Size of the Aorta in Warm- Blooded Animals. 51 



Table XII. — Man (grouped). Thoma's Observations.* 



Group. 



Number of individuals 

 in group. 



Average body weight. 



Average radius of aorta. 



Average area of aortic 

 cross-section. 



-2. 



% 

 ii 



Aortic cross-section as 

 percentage of body 

 weight. 



Cross-section calculated. 

 (* = 5 -03.) 



Difference between 

 cross-section calcu- 

 lated and observed. 



Cross-section calculated 

 as percentage (1 '052) 

 of body weight. 



Difference between 

 cross-section calcu- 

 lated and observed. 







grms. 



mm. 



sq. mm. 









per cent. 





per cent. 



A 



7 



8941 



6 1 



117 



4 99 



1 309 



116 



"86 



94 1 



24 34 



B 



9 



11950 



6 7 



141 



5 07 



1 18 



142 1 



77 



125 7 



12 17 



C 



5 



13630 



7 25 



165 



4 75 



1 211 



155 8 



5 91 



143 4 



15 06 



D 



3 



17510 



7 65 



184 



5 08 



1 051 



185 7 



92 



184 2 



Oil 



E 



4 



43250 



10 -2 



326 



5 4 



754 



349 6 



6 75 



455 



28 35 



F 



5 



49000 



11 2 



394 



4 87 



804 



381 5 



3 28 



515 5 



23 57 









Avera 



ge - 



5 03 



1 052 





3 08 





17 27 



* Thoma's data are printed in light type. The figures calculated by us are printed in heavy 

 type. 



calculated figures is 3 - 08, while it is 17*27 (more than five and a-half times as 

 great) if the area be calculated as a percentage of the body weight. 



If the value - 7l be taken for n the value of k becomes 5 - 55, and with an 

 n of 0"72 k is 6 - 13. Taking n as 071 the average percentage deviation of the 

 observed values from tbose calculated by our formula is 3 - 16 as compared 

 with the deviation of 3'08 per cent, with n equal to - 70. Or if the appropriate 

 allowance be made for the number of individuals in each of the groups, the 

 figures for the average percentage deviation of the observed values from the 

 theoretical values given by our formula are 2 - 69 with an n of 0"70 and 2 - 73 

 with n of 0"7l, indicating the fact that the value 071 for n is only very 

 slightly less good in these observations than the value - 70. 



Thoma himself, who, in his great monograph (7) on the size and weight of 

 the various parts of the human body under normal and diseased conditions, 

 endeavoured to establish a definite quantitative relation between the body 

 weight and the aortic radius, defined the correlation which he found to exist 

 in the statement that the body weight divided by the cube of the aortic 

 radius was approximately constant over a wide range of weight. 



This he expressed in the formula W/r 3 = K. The formula was purely 

 empirical, and possessed no special biological significance, though it repre- 

 sented the experimental data in an extremely satisfactory manner. It will 

 be seen, however, that it is readily transformable into the formula 

 W ! /7rr 2 = k, which is the formula deduced by us from our observations 



E 2 



