No. 641] 



THE DURATION OF LIFE 



483 



imentation, wliicli are critically standardizGcl and have 

 been used in the work which will be described in sub- 

 sequent papers. 



3. The general form and characteristics of the mortal- 

 ity curves of Drosophila, presenting mortality tables for 

 certain strains. 



4. The influence of certain phases of the experimental 

 technique employed upon the results. 



Specific problems regarding the duration of life will be 

 presented and discussed in the subsequent papers in the 



Literature 



The earliest mention we have found of observations on 

 the duration of life of Drosophila is a casual reference 

 in a paper by Moenkhaus (10) published in 1911 in which 

 he makes the following statement in connection with egg 

 counts : We have kept females alive 153 days." There 

 are no details of any kind, as to conditions or numbers 

 involved. 



The first paper to make more than casual reference to 

 the duration of life of I)yns,>p],'ihi is a ])aper published in 

 1913 by Hyde (11). In ^tudyin- intility and sterility in 

 different strains of flies he found two strains which dif- 

 fered to a marked degree in res])t'('t of length of life, and 

 made crosses to study the behavior of tho sliortcred 

 length of life of the mutant " trniicalo in lid'cdity. His 

 numbers are small, but they show the charactci-istic in- 

 creased vigor of F, hy1)ri(ls. Tlir shorter average age 

 of the lumped F/s indicates that there have segregated 

 out in the F. generation >oine short-lived flies. His data, 

 however, do not give, or aMow us to get, sepni-ate averages 

 for the truncate F.'s and the normal wingtMl i './s. 



His data are summarized in Table I. 



In 1914 Baumberger (12) published a papei- in whieh 

 he gives data on the length of life .>f different onh^rs of 

 Inserts without food a> affeeted i.y different e.)nMant tem- 

 peratures, and hy expoMire to two different temperatures. 

 Since tlie insects were caught in a net as ima-o.'s Die total 



