6 Protection of Meat Commodities against Bloicjlies 



menting with a wide range of repellent substances against blowflies, 

 used precipitated chalk as a vehicle for the chemicals. In most cases, 

 the chalk plus chemical conferred immunity during one to four days, 

 complete immunity being obtained by the use of copper carbonate, 

 nitrobenzene, picric acid, creosote, sinapis oil and aniseed oil. It must 

 be noted, however, that precipitated chalk by itself will protect fresh 

 meat so long as it remains unsaturated by exuding juices either of muscle 

 plasma or of putrefaction, and that when chemicals are present that 

 can exert an inhibiting action upon bacterial activity, putrefaction is 

 delayed and the chalk will last a long time before becoming saturated. 

 That is to say, the substances recommended by Cooper and Walling 

 may not necessarily be repellent to the fly, the apparent repellent action 

 being due possibly to the restraining effect exerted by the chemicals 

 upon bacterial activity, and the action of the precipitated chalk in keep- 

 ing the meat surface dry. 



Weather sunny, cool in afternoon. 

 Wet night, fine morning. 



'•Heavily" signifies three or more clusters of eggs. 

 "Considerably" signifies one or two clusters of eggs. 

 "Slightly" signifies scattered eggs, rarely exceeding 12 or 15. 



In the case of powdered boracic acid or powdered salt, the drying 

 effect is soon lost owing to the solvent action of the meat juices and no 

 success, as repellents, was observed in my experiments with these sub- 

 stances. 



Cooper and Walling, and Miss Lodge, however, assert positively that 

 boracic acid is repellent to blowflies. 



Weak formalin was decidedly repellent, but hardly applicable to 

 meat commodities. 



