1912.] The Size of the Aorta in Warm- Blooded Animals. 47 



female of the same weight. This is of special interest in view of the fact 

 that a difference of the same size and character was observed by two of 

 us in the blood volume of male and female rabbits. It may be noted, 

 further, in this connection that, so far as we have yet ascertained from 

 our data, the heart in the male animal is somewhat larger tban in the female 

 of the same body weight and species. 



Table VII.— Ducks (individuals). 



6 





[so 

 '8 



o3 



Radius of aorta. 



Area of aortic cross- 

 section. 



h 



I! 



Aortic cross-section as 

 percentage of body 

 weiglit. 



a? 



StS 



o 



1 II " 



m 

 O 



Difference between 

 cross-section calcu- 

 lated and observed. 



Cross-section calculated 

 as percentage (.1 '5(>) 

 of body weight. 



Difference between 

 cross-section calcu- 

 lated and observed. 







grin. 



mm. 



aq. mm. 









per cent. 





per cent. 



1 





70 



764 



1 S4 



10 66 



2 62 



1-82 



82 



1 09 



68 04 



1 2 





70 



758 



1-8 



10 -87 



2-57 



1 -82 



1 1 



1 09 



64-84 



3 





70 



745 



1 74 



11 -21 



2 49 



1 -82 



4*4 



1 -09 



59 34 



4 





520 



1 -56 



7 64 



10-42 



1 47 



7-38 



3 52 



8 11 



5 8 



5 





600 



1 66 



8-6 



10 -23 



1 -43 



8-25 



4-24 



9-36 



8-12 



6 



? 



1180 



1 -99 



12 42 



11 39 



1 05 



13 14 



5-48 



18 -41 



32 -45 



7 



<J 



1330 



2 -14 



14 3 



10-75 



1 -08 



14 3 







20 -75 



31 09 



8 



? 



1420 



2 16 



14-72 



10 -93 



1 04 



14 -96 



1 6 



22 -15 



33 -54 



9 



? 



2070 



2 -47 



19 15 



10 -91 



6 93 



19 -48 



1 -69 



32 -29 



40 -69 



10 



? 



2850 



2-86 



25-8 



10-16 



0-91 



24 37 



5-87 



44 46 



41 -97 



AVerage 



10 75 



1 56 





2-87 





38 59 



B. Birds. — Table VII gives the figures for the aortas of 10 ducks, ranging 

 in weight from 70 grm. to 2850 grin. (i.e. increasing more than fortyfold). 

 The average aortic constant (I:) is 10 75 with an n (best n) of - 70, and the 

 average aortic percentage is 1*56. The variations of the aortic constant are 

 small and show no periodicity, but the aortic percentage decreases very 

 greatly and with absolute regularity as the animals increase in weight. 

 When the aortic area (A) is calculated by our formula, the average deviation 

 of the observed from the calculated figures is only 2 - 87 per cent., while it is 

 38'59 per cent, (more than 13 times as great) if the area be calculated in 

 per cent, of body weight. 



If the value 0'71 be taken for n, k becomes 11'54 and the average deviation 

 between calculated and observed values is 3 - 12 per cent. ; with n equal to 

 - 72, h is 1219. That the value 0'71 for % is very nearly as good as the 

 " best " n (0'70) is shown by the fact that while the average deviations per 

 cent, are 2'87 and 312 respectively with n = 070 and n = - 71, the mean 



