1912.] The Size of the Trachea in Warm- Blooded Animals. 59 



weights, the tracheal radii, and the tracheal areas of the animals in each 

 group averaged. The other figures are calculated from these average values. 



It is found that, under these circumstances, the best n is 071, and the 

 average value of k is 21'3. Using these values for n and h, the average 

 deviation between the calculated and the observed figures is 5"46 per cent., 

 while it is 22 - 49 per cent, if the tracheal area (T) be calculated as a 

 percentage. (0*965) of body weight. If the value of n be taken as 0"70, k is 

 20*1, but, if n be taken as - 72, k becomes 22 - 5, and the corresponding 

 average percentage deviation is 5 - 76 instead of 5'46. If, however, the 

 appropriate allowance be made for the number of individuals in each group, 

 the percentage deviations become 4 - 22 (with n = 072) and 4 - 24 (with 

 oi = 0*71). So that the value - 72 for n is in reality slightly better than 

 0'7l, as it was in the case of the individual animals. 



Further, it will be observed that, while the k exhibits no periodic variation 

 as the weight of the animal increases, the tracheal percentage (tracheal area 

 expressed in per cent, of body weight) decreases very greatly and with 

 absolute regularity from 1"51 to 0'67l. 



Table III. — Eabbit (individuals). 



d 



Sex. 



Body weight. 



Radius of trachea. 



Area of tracheal cross- 

 section. 



EH 



p 



fc 

 II 



»4i 



Tracheal cross-section 

 as percentage of body 

 weight. 



Cross-section calculated. 

 (k = 12 -5.) 



Difference between 

 cross-section calcu- 

 lated and observed. 



Cross-section calculated 

 as percentage (0 - 83) 

 of body weight. 



Difference between 

 cross-section calcu- 

 lated and observed. 







grm. 



mm. 



sq. mm. 









per cent. 





per cent. 



1 



? 



940 



1 -8 



10 2 



11 8 



1 -084 



9 62 



6-02 



8-2 



24-4 



2 



? 



970 



1 -76 



9-69 



12 -8 



1 -ooi 



9-92 



2-32 



8-47 



14 -4 



3 



? 



1100 



1 -88 



11 -1 



12 -2 



1 -009 



10-8 



2-78 



9-6 



15-62 



4 



3 



1330 



1 96 



12 -06 



12 8 



0-906 



12 -3 



1-95 



11 -62 



3 79 



5 



3 



1420 



2 09 



13 -8 



11 6 



0-972 



12 -8 



7-82 



12 -4 



11 -3 



6 



9 



1600 



2 "23 



15 6 



11 2 



0-975 



14-0 



11 -4 



13 -97 



11 67 



7 



? 



1880 



2 -1 



14 -0 



14 -0 



0-745 



15-7 



10 -8 



16 -41 



14-7 



8 



? 



2040 



2 -45 



18 9 



11 -o 



0-927 



16-4 



13-9 



17 -82 



6-06 



9 



3 



2080 



2 -22 



15 4 



13 6 



0-74 



16-8 



8 -34 



18-15 



14 6 



10 



S 



2180 



2-26 



16 -1 



13 1 



0-739 



17 -4 



7-47 



19 03 



15-39 



11 



? 



2280 



2 "42 



18 -4 



12 1 



0-807 



17 -9 



2-79 



19 9 



7 -54 



12 



¥ 



2750 



2-58 



20 -8 



12 3 



0-76 



20 -4 



2 -45 



24 -0 



12 -9 



13 



3 



2970 



2-54 



20 -3 



13 3 



0-684 



21 -5 



5 -58 



25 -92 



21 -68 





12 -5 



0-873 





6 -43 





13 -39 



Table III gives the figures and calculations for the tracheas of 13 rabbits 

 (tame) ranging in weight from 940 grm. to 2970 grm. {i.e. increasing more 



