50 



Messrs. Dreyer, Ray, and Walker. 



[Sept. 30, 



periodic, but the aortic percentage falls gradually though not quite regularly 

 from T49 to 1'35. Using the above values for n and h, the average deviation 

 of the observed figures from the calculated is T28 per cent., while it is 2 - 99 

 per cent, (more than twice as great) if the area be calculated as a percentage 

 of the body weight. 



Table XI. — Sparrows (individuals). 



6 



Body weight. 



Radius of aorta. 



Area of aortic cross- 

 section. 



% 



II 



Aortic cross-section as 

 percentage of body 

 weight. 



Cross-section calculated- 

 (k = 22-6.) 



Difference between 

 cross-section calcu- 

 lated and observed. 



Cross-section calculated 

 as percentage (1 - 77l) 

 of body weight. 



Difference between 

 cross-section calcu- 

 lated and observed. 





grm. 



mm. 



sq. mm. 









per cent. 





per cent. 



1 



22 "05 



0-35 



0-385 



23 1 



1 -743 



0-398 



3-26 



0-391 



1-53 



2 



22 -55 



0-366 



0-42 



21 -8 



1-782 



0-405 



3-7 



0-399 



5 -26 



3 



23 -1 



0-398 



0-487 



19 -1 



2 -105 



0-412 



15 -77 



0-409 



19 -03 



4 



24 -6 



0-414 



0-537 



18 -1 



2-098 



0-429 



25-18 



0-436 



23 -2 



5 



26 -55 



0-35 



0-385 



26 -6 



1 -45 



0-453 



15 -01 



0-47 



18 -09 



6 



26 -6 



-35 



0-385 



26 -7 



1 -448 



0-454 



15 -2 



0-471 



18 -3 



1 



22-6 



1-771 





13 -02 





14 -24 



Table XI gives the figures for the aortas of six sparrows ranging in weight 

 from 22 - 05 grm. to 26'6 grm., a very small range indeed, but the best which we 

 were able to obtain at the time. The average aortic constant (k) is 22 - 6 with 

 an n (best n) of 071, and the average aortic percentage is T771. The variations 

 of the aortic constant show no periodicity. When the aortic area (A) is 

 calculated by our formula the average percentage deviation between the 

 calculated and the observed figures is 13 - 02, and it is 14*24 if the area be 

 calculated as a percentage of body weight. 



If n be taken as 0'70 the value of h is 21 - 9, and with an n of 0'72 k is 23"4. 



C. Thoma's Observations on Man. — Table XII contains the figures for the 

 aortas of 33 human individuals calculated from the grouped observations 

 published by E. Thoma (7). The individuals in question ranged in age from 

 two months to 29 years and the range in weight of the groups is from 

 8941 grm. to 49,000 grm. The best n is - 70, which gives an average value 

 for Je of 5'03. The variations in the aortic constant are without periodicity, 

 but the aortic percentage falls gradually though not quite regularly from 

 1*309 in the lightest group to 0'804 in the heaviest. Using these values 

 for n and h, the average percentage deviation of the observed from the 



