EXPERIMENTAL STUDIES ON THE DURATION 

 OF LIFE 



III. The Effect of Successive Etheeizations on the 

 Duration of Life of Deosophila^ 



PROFESSOR RAYMOND PEARL AN'D SYLVIA L. PARKER 

 Purpose and Plan of Experiments 

 In any experimental work of a genetic character on 

 Drosophila, it is often necessary to anesthetize the flies 

 which are to be used in an experiment for a sufficiently 

 long time so that they may be sexed and sorted into dif- 

 ferent groups for the purpose of making matings, etc. 

 It has been shown by Morgan (33) that this procedure 

 has no effect upon the causation of morphological mu- 

 tations, the inheritance of which he has studied (9). The 

 effect might, however, conceivably be quite different in 

 the case of a physiological character like duration of life. 

 Any one who has undergone a major surgical operation 

 feels that anesthetization is at least immediately a rather 

 profound physiological disturbance. Unfortunately, so 

 far as we are aware, no accurate determinations have ever 

 been made to show whether in man one or more anes- 

 thetizations changes the expectation of life. As a mat- 

 ter of fact, there are presumably no human data on the 

 point available in any such amount as would be necessary 

 for actuarial determinations, because in man anestheti- 

 zation is, generally speaking, only undertaken in connec- 

 tion with surgical operations of greater or less severity, 

 so that if we did have statistics of expectation of life of 

 persons who had been anesthetized, there would always 

 be involved the two factors of anesthetization and oper- 



1 Papers from the Department of Biometry and Vital Statistics, School 

 of Hygiene and Public Health, Johns Hopkins University, No. 54. For 



second paper in the series (32). 



273 



