June 11, 1915] 



SCIENCE 



875 



TABLE OF KECORDED EESULTS OF WORK WITH PLIES 



observed from time to time for deposits. Thia 

 method proved too cumbersome, and another 

 metbod was later employed, tbat of isolating 

 two or three gorged females in a 2-oz. vial 

 over a portion of egg-free manure. Manure 

 from the same dropping was used for all vials 

 in each series. 



As egg batches were deposited their removal 

 followed as soon as they were observed. 



Each batch was divided into three parts, and 

 the eggs placed in vials on about an inch and 

 a half of egg-free manure and incubated at 

 20°, 30° and 35° 0., respectively. 



The manure was examined twice daily, morn- 

 ing and afternoon, by carefully stirring up 

 the manure, and any changes were recorded. 

 Records were made under the following heads : 

 Date of incubation; date of appearance of 

 larvse; date of appearance of pupae; date of 

 appearance of adult. 



The first series of experiments was greatly 

 hampered by fluctuation in temperatures of 

 the incubators and by the appearance of molds 

 in the fly cultures which in almost all cases pre- 

 vented the completion of the life cycle. These 

 first experiments are omitted and only those 

 broods that came through without mishap or 

 nearly so are recorded. 



The accompanying table gives the average pe- 

 riods for each stage at the three temperatures. 

 (Complete data are appended.) 



EXPERIMENTS WITH MOSQUITOES 



Batches of eggs were collected every morn- 

 ing from a rain barrel and each batch was 

 divided into three portions, and each portion 

 placed in a 2-oz. vial on the surface of a manure 

 infusion. The manure infusion was selected 

 from a series of tested media since it proved a 

 most satisfactory medium for the larvse and 

 pupae. About li grams of manure were added 

 to 40 c.c. of tap water. The vials were incu- 

 bated at 20° C, room temperature, and 30°, 

 respectively; 35° proved fatal to these insects 

 in most cases. The vials at room temperature 

 were kept out of air currents by placing them 

 in a box. This precaution, however, did not 

 prevent an evening drop in temperature of 5 to 

 8 degrees, but on the whole the room tempera- 



