300 HENRY H. DONALDSON 



The corresponding determinations for man based on the data 

 given by Humphry ('58) and plotted by Duckworth ('04) show 

 a range from 100 per cent at birth to about 70 per cent in adults. 

 Thus the intermembral ratio is about the same in these two forms, 

 despite the very different use of the fore limbs in the two cases. 

 This similarity is of course a mere coincidence, as the corre- 

 sponding ratios among the Simiidae, zoologically closest to man, 

 are all much higher. 



In the case of the radio-humeral index, the value in man is 

 about 74 per cent at birth and 72 per cent at maturity, while 

 for the rat the record, which is slightly sinuous, reaches a maxi- 

 mum of 95 per cent at a body weight of 15 grams, and then in 

 general falls to about 90 per cent at maturity (chart 22, table 

 27) . The ulno-humerus ratio for the rat follows a like course 

 from a maximum of 122 per cent at 35 grams of body weight to a 

 minimum of 113 per cent at maturity (chart 22, table 27). 



If we turn now to a consideration of the bone relations in the 

 leg, we find that the tibio-femoral index for man ranges from 

 about 81 per cent at birth to 80 per cent at maturity, while for 

 the rat the corresponding ratios are 126 per cent at 25 grams of 

 body weight and 106 per cent at maturity. Despite the fact, 

 therefore, that the intermembral ratios are rather similar, the 

 radius, ulna, and tibia all have a greater relative length in the 

 rat than in man. 



The relation of the stature in man at maturity to that of the 

 several long bones of the limbs has been carefully worked over by 

 Manouvrier ('92). His tables are given by Testut ('96), and 

 further refinements in the application of the data have been 

 elaborated by Pearson ('99). 



Owing to the difference in the form of man and the rat, no 

 really comparable measurement can be made on the rat, but if it 

 is desired to recover the body length (nose-anus length) of the 

 rat in any case from the length of one or more of the leg bones, 

 this can be done by the aid of table 29, which gives the ratios 

 of the body length in relation to the sum of the lengths of the 

 humerus plus radius, humerus plus ulna, or femur plus tibia. 



