126 SURVEY OF INVERTEBRATES 



of developnioiit in air of ijupac that lacked oxygen for 

 varying periods with that required by pupae kept during 

 the whole time in air and found that after 3 days in 

 the absence of oxygen the total time required for devel- 

 opment in air was shorter tlian in the controls. After 4 

 days without oxygen, however, a retardation became ap- 

 parent and the few emerging adults appeared damaged. 

 Finally, after 5 days no adults emerged; the pupae had 

 succumbed to the lack of oxygen. 



According to Lobaschow (1934) periods of asphyxia- 

 tion in the larval and pupal stages of DrosopJiila in- 

 creased the numbers of lethal and semi-lethal mutations. 

 Margolis (1939) kept bar-eyed fruit flies for varying 

 lengths of time (2 to 5 days), during the egg-larval pe- 

 riod, at a reduced pressure (half an atmosphere) and 

 found a small decrease in the number of facets on the 

 eye. Although the decrease was in most cases not sta- 

 tistically significant, he is inclined to regard it as real, 

 since an increase in the partial pressure of oxygen had the 

 opposite effect. 



Schlottke (1934) studied the influence of various oxy- 

 gen concentrations upon the larvae and pupae of Hahro- 

 bracon juglandis. He found that the larvae did not de- 

 velop unless the atmosphere contained more than 4 per 

 cent of oxygen, a figure somewhat higher than that men- 

 tioned above for DrosopJiila. When the atmosphere con- 

 tained 8 or 12 per cent oxygen there resulted an in- 

 creased pigmentation of the animals. This result, how- 

 ever, is not specific since an abnormally high oxygen ten- 

 sion had the same effect. 



Finally, Snell's (1932) investigations on the lumines- 

 cence of Photuris pennsylvanica may be mentioned. He 

 observed that the duration of the light flash depends on 

 the oxygen tension, a lowering of the tension below 20 

 mm. of Hg resulting in flashes of longer duration. At 

 tensions below 4 mm. of Hg flashes were not observed 



