398 THE AMERICAN NATURALIST [Vol. LVI 



46. Carrel, A. and Ebeling, A. H. The Multiplication of Fibroblasts in vitro. 



Jour. Exp. Med., Vol. 34, pp. 317-337, 1921. 



47. Id. Heterogenic Serum, Age, and Multiplication of Fibroblasts. IMd., 



Vol. 35, pp. 17-38, 1922. 



48. Bacot, A. W. and Harden, A. Vitamin Eequirements of Drosophila. 



I. Vitamines B and C. Biochem. Jour., Vol. 16, pp. 148-152, 1922. 



VI. A Comparison of the Laws of Mortality in 



Drosophila and in Man 



In the first of these Studies (27) there were presented 

 for the first time, so far as I am aware, complete life 

 tables for any other organism than man. Up to the pres- 

 ent time there have been presented in the published re- 

 sults of the work of this laboratory on Drosophila (27, 

 32, 44, 49, 50) exact determinations of the duration of 

 life in 24,329 individual flies. This is a statistically re- 

 spectable mass of material, and warrants some general 

 discussion. 



In the first study a rough, purely graphical compari- 

 son of the Ix lines of the Drosophila and certain human 

 life tables was instituted. This comparison, rough as 

 is was, made apparent at once the fact that there was a 

 fundamental similarity in laws of mortality in these two 

 organisms. 



It is my purpose in the present paper to make a more 

 exact comparison of the values of the life table functions 

 in the two cases. It will be seen that the similarity is 

 even closer than was supposed from the rough compari- 

 son, and that in fact we are dealing here with qualita- 

 tively identical expressions of an obviously fundamental 

 biological law. 



Upon what basis shall any life table function, say L, 

 of the Drosophila life table be compared with that of 

 man? The life span of one of these organisms is best 

 measured in days, while that of the other is measured in 



PROFESSOE RAYMOND PEARL 



I 



II 



