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THE AMERICAN NATURALIST [Vol. LV 



way of general principles to the science of biology. In 

 outlining the plans of the department at the time of its 

 inauguration provision was made, as a major element in 

 the whole organization scheme, for experimental work on 

 the duration of life, to parallel as closely as possible, in 

 respect of its problems and foci of interest, the statistical 

 work of the department. The present paper is the first 

 of a series which will appear dealing with the exper- 

 imental side of our work. 



Oviginally it was planned to use mice as the material 

 for experimentation on the duration of life, and a large 

 and flourishing colony was bred up in accordance with the 

 most critical genetic standards for experimental material. 

 Just as the colony was ready to start definitive exper- 

 imentation with, an accident completely destroyed it. 



It was then decided, after advising with a number of 

 persons, notably Professor T. H. Morgan and Dr. Jacques 

 Loeb, to take up Drosophila as material for the extensive 

 program of experimental work which we had planned. 

 This organism has the great advantage over any other 

 wliich could be used, that its genetic behavior and poten- 

 tialities are more thoroughly understood than those of 

 .•iii> other animal, thanks to the epoch-marking researches 

 <.t' Moi-gnii (D) and iiis students. It has tiie further great 

 a.l\ aii1a-c that uiuhT .-rrtaiii (M.ii.lit hms. which we now 

 rath.'i' ch-aily uii.h'i^laii.K il> (hii'ati..ii of life, both in 

 I'cspccl of means and of the /, or /Ir distributions of a life 

 table, is extraoixliuarily like that oL' man, with one day in 

 the life of the fly corresponding roughly to one year in 

 the life of man. 



The first paper in tlie series aims to present, as a back- 

 ground of reference foi' further contributions, the follow- 

 ing essential items: 



1. A brief review of what has ])een noted by previous 

 workers regardin- duration of life in DrosnphUn, ami 

 other insects in far a^ the ^h^rrvat inn^ aie .|iiantita- 

 tive in character. 



-1. The details of our material and methods of exper- 



