II. Eltringham 



447 



appearance of the completed traps is shown in the photograph herewith, 

 which represents those on the laboratory ground. It may be remarked 

 that nnbleached cheese cloth is superior to the bleached quality, in 

 that it is cheaper, stronger, and transmits less light. 



Fig. 3. 



Experiment I. On .June 22nd a heap was started at the laboratory, 

 one barrow load of horse manure from neighbouring army stables being 

 placed upon it daily. By the 25th the temperature of the centre of 

 this heap had risen to 75° (all temperatures are given on the Centigrade 

 scale) and on the 28th it had fallen to 65". The temperature fell slowly 

 to 54° on July 6th, when the heap wa.s completely covered in, the 

 quantity of manure being estimated at about 14 cwt. On July 8th the 

 temperature of the heap was 47°, and on the 9th two flies were found 

 in the top trap, one being M. domeslira. On July 11 th one more of 

 the same species hatched out. On July 21st the temperature of the 

 heap was 20°, and on the 26th 2.3°. On .July 29th the heap was opened 

 out and cleared away. The total flies of all kinds which hatched from 

 this heap numbered 16 and were of the following species: 



