No. 561] SHORTER ARTICLES AND DISCUSSION 573 



Experiment 1. — 104 larvae (53 T. molitor and 51 T. obscuris). Kept at a 



vious heating at 41°-42° for 4 hours in which no record was kept of the 

 number dying. Count made 24 hours after last heating. 



Barely alive none 12 



Dead 25 13 



Per cent, dead 100 52 



Experiment 3.— 441 larva; (204 T. obscuris and 237 T. molitor). Heated 

 at 41.5°-42° for 3.5 hours. 



















176 ! none 





















Dead." 











Per cent, dead 



Per cent, barely alne 













Inasmuch as these experiments show a remarkable differential 

 mortality, two other series of experiments were undertaken, in 

 one of which the external influence used was exposure to cold for 

 a long period of time and in the other set, exposure to an atmos- 

 phere of pure carbon dioxide. 



Experiments with Cold 

 Two experiments were made on the influence of cold as affect- 

 ing the death rate. Two large Stender dishes, each of which con- 

 tained 50 T. molitor and 50 T. obscuris, were placed inside of a 

 battery jar, together with a maximum and minimum thermom- 

 eter, the top of the jar was closed with a sheet of rubberized cloth 



