A STUDY OF OXYGEN METABOLISM. 



441 



work was undertaken in localities removed from centers where 

 flies are grown. These may be called the "non-inbreds." The 

 remaining five stocks had been inbred for a number of years 

 before being received and, as some of these are well known, the 

 following table of sources may be of interest. 



TABLE I. 



SHOWING DERIVATION OF EXPERIMENTAL MATERIALS. 

 NON-INBREDS. 



INBREDS. 



Owing to some preliminary difficulties, work was not begun 

 until December, 1923, or until the non-inbred stocks had become 

 inbred for several generations. Thereafter readings were con- 

 tinued, with interruptions, until December, 1924, when the 

 experimental work was concluded. The chronological distribu- 

 tion of the work is without significance to our study and will not 

 be entered into. 



The pupae of Drosophila melanogaster are so small that it is 

 impracticable to make an extensive series of measurements of 

 oxygen consumption on single pupae, hence lots of 10 or fewer 

 pupae were used for each determination. Readings were taken 

 over a period of 4 or 5 hours each day throughout the duration 

 of pupal life. Data were collected for 160 lots of pupae. 



The stock flies were grown in mass culture in large quinine 

 bottles and kept at room temperature. The experimental pupae, 

 however, were always the products of single matings. From 

 time to time the flies in a culture bottle were removed and 

 matings were made up from new flies as they appeared which 



