48 



Messrs. Dreyer, Ray, and Walker. [Sept. 30, 



deviations calculated by the method of least squares are 3"67 and 3 - 63 per 

 cent, respectively with the same values of n. That is to say that the value 

 071 gives a very slightly smaller mean deviation than the value 070. 



Table VIII.— Fowls (individuals). 



6 

 |zq 



X 



<D 



Body weight. 



Eadius of aorta. 



Area of aortic cross- 

 section. 



o 



II 



Aorlic cross-section as 

 percentage of body 

 weight. 



O £ - 



II II 



m 

 p 



5 



Difference between 

 cross-section calcu- 

 lated and observed. 



Cross-section calculated 

 as percentage (1 -14) 

 of body weight. 



Difference between 

 cross-section calcu- 

 lated and observed. 







grm. 



mm. 



sq. mm. 









per cent. 





per cent. 



1 





40-6 



0-462 



0-669 



21 -51 



1 -648 



0-679 



1-47 



0-463 



54 13 



2 





42-7 



0-462 



0-669 



22 -31 



1 -567 



-704 



4-97 



0-487 



43 -53 



3 





43 -9 



-484 



0-736 



20 -54 



1 677 



0-718 



2 -51 



0-5 



47 -2 



4 



¥ 



919 



1 -45 



6-6 



20 -61 



0-718 



6 -41 



2-96 



10 -48 



37 -02 



5 



? 



1580 



1-72 



9-3 



21 -61 



0-589 



9 48 



1-9 



18-01 



48 -31 



6 



? 



1598 



1-77 



9-81 



20 -65 



0-614 



9-55 



2 -72 



18 -22 



46-16 





21 -21 



1 -14 





2-76 





46 06 



In Table VIII are given the figures for the aortas of six fowls, ranging in 

 weight from 406 grm. to 1598 grm. (i.e. increasing nearly fortyfold). The 

 average aortic constant (k) is 21-21 with an n (best n) of 072, and the 

 average aortic percentage is 1*14. The variations of the aortic constant are 

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

 greatly and almost regularly from 1*648 in the lightest animal to 0614 in the 

 heaviest. When the aortic area (A) is calculated by our formula the average 

 deviation of the observed from the calculated figures is only 276 per cent., 

 while it is 46'06 per cent, (nearly 17 times as great) if the area be calculated 

 in percentage of body weight. 



With n taken as 071, k becomes 20 - 08 and the average percentage deviation 

 between observed and calculated figures is 3*28. 



Table IX contains the figures for 10 ptarmigan purchased from a game- 

 dealer. These were birds which had been shot, and they show the greatest 

 range of weight we were able to obtain, namely, from 470 grm. to 710 grm. 

 The average aortic constant (k) is 11*4 with an n (best n) of 071, and the 

 average aortic percentage is 1*4. The variations of the aortic constant show 

 no periodicity, but the aortic percentage decreases from T66 in the lightest 

 to 1"23 in the heaviest animal. When the aortic area (A) is calculated by 

 our formula the average deviation of the observed from the calculated figures 



