DESTRUCTION OF FLY LARVJE IN HORSE MANURE. 3 



pupse in each pile was counted about eight days after the last treat- 

 ment. A sample of 200 pupse from each pile was kept in the labora- 

 tory, and the percentage of emergence determined. From these data 

 the apparent larvicidal effect was calculated. For some of the New 

 Orleans experiments, cages (PI. I, fig. l,p. 16) were constructed to cover 

 the piles, and instead of counting the number of pupse the flies were 

 allowed to emerge and were caught in traps attached to the tops of 

 the cages. Temperatures and samples for analysis were taken 

 through the armholes in the sides of the cages. Soil was banked 

 against the base of the cages to prevent the escape of maggots and flies. 

 Chemical and bacteriological analyses were made of samples of 

 manure from most of the cage and open-pile experiments.. 



SAMPLING FOR qHEMICAL AND BACTERIOLOGICAL ANALYSES. 



It is very evident that a manure pile with the unequal distribution 

 and great variation of its physical and chemical constituents will 

 necessarily be exceedingly difficult to sample, especially to secure 

 from it a few hundred grams which will be thoroughly representative. 

 An attempt was made to secure representative samples by taking 

 equal portions of manure from three different parts of the pile, 

 spreading them on a clean sheet of paper, and finely dividing and 

 thoroughly mixing them. When the material appeared quite uni- 

 form the sample was quartered. One quarter was then cut into 

 half-centimeter lengths with clean shears. The straw or shavings 

 were cut with the other material. When this operation was com- 

 pleted the sample was again thoroughly mixed. For chemical 

 analysis the material was twice passed through a grinder. Both 

 bacteriological and chemical examinations were made on the same 

 sample. As the bacterial content of manure is very high, no attempt 

 was made to work under absolutely sterile conditions, because the 

 contamination arising from ordinary handling of the material was 

 of no importance when compared with the great number of organisms 

 present. However, precautions were taken to prevent excessive 

 contamination by using clean paper, shears, etc., for each sample. 



BACTERIOLOGICAL EXAMINATION. 



Two 10-gram samples of the manure, prepared as just described, 

 were taken for each bacteriological determination. One of the 

 10-gram samples was dried at 100° C. for one hour to determine the 

 percentage of solids. The other sample was brushed into a 2-liter 

 flask containing 1 liter of sterile water. The flask was then vigorously 

 shaken for five minutes and again, after a five minute interval, for 

 three minutes. A 1-c. c. sample was then withdrawn and run into 

 100 c. c. of sterile water. Five dilutions were prepared, ranging from 

 1 part in 10,000 to 1 part in 100,000,000. A duplicate series of Petri 

 dishes was then prepared from these dilutions and standard beef agar. 



