1912.] The Size of the Aorta in Warm-Blooded Animals. 55 



Table XV. — Mean Deviations. 



Species. 



Best n. 



Mean deviation using 

 best n in the formula 

 A = W"jk. 



Mean deviation when 



aortic area is cal- 

 culated in percentage 

 of body weight. 



Grumea-pi** ■ individual 



-71 



21 -51 



25 -76 





72 



3 -91 



17 -81 





-71 



15-75 



23 -54 



„ grouped 



0-72 



1-8 



20 -45 



Rabbit (tame) : individual 



0-71 



19 -47 



32 -08 



„ grouped 



0-71 



11 -92 



29 -96 





0-70 



3-67 



45 -93 





0-72 



3 -25 



50 -7 





0-71 



8 -41 



9-1 





0-72 



1 -78 



4-11 





0-71 



16 -51 



17-84 





0-70 



4-32 



21 -57 



Average mean deviation taking J 

 best n. \ 



individuals ... 



14-21 

 4-75 



29 -27 

 18-78 



formula was as much as 10 per cent., the aortic area would probably be 

 abnormal, and if it amounted to 15 per cent, it would be almost certain 

 that the aortic area was abnormally large or small. But if the measure- 

 ments were expressed in percentage of body weight it would only be 

 possible to say with the same degree of certainty that the aortic area of 

 an animal was abnormal when it differed from the calculated value by 

 60 per cent. 



Conclusion. 



Within a wide range of weight in any given species of warm-blooded 

 animal the sectional area of the lumen of the aorta is proportional to the 

 body surface, and can be calculated from the body weight by means of the 

 formula A = W n /k, where n has the value 0-70-O72 and k is a constant to 

 be ascertained for each particular species. 



REFERENCES. 



1. Dreyer, G., Ray, W., and Walker, E. W. Ainley, 1912, "The Relation between the 



Sectional Area of the Trachea and the Body Weight in certain Animals," 

 ' Journ. Physiol.,' vol. 45, p. vii. 



2. Dreyer, G., and Ray, W., 1910, "The Blood Volume of Mammals, as determined by 



Experiments upon Rabbits, Guinea-pigs, and Mice, and its Relationship to the 

 Body Weight and to the Surface Area expressed in a Formula," ' Phil. Trans.,' 

 B, vol. 201, p. 133. 



3. Dreyer, G., and Ray, W., 1911, "Further Experiments upon the Blood Volume of 



Mammals and its Relation to the Surface Area of the Body," ' Phil. Trans.,' B, 

 vol. 202, p. 191. 



