XXXli, '21] ENTOMOLOGICAL NEWS 305 



out of the direct light. If too much water was placed in the 

 cage, the sand, sawdust and blotting paper would all help to 

 absorb it, and the next day the cage would not be moistened. 



The cage used for pupae was the same used by Mr. Lyon. 

 (No. 3) in his experiments with the cat flea, namely: A glass 

 funnel with wire pan within ; the cage containing pupae was 

 placed on the pan. leaving a clear space around the sides, and 

 the funnel was covered to prevent hatched fleas from escaping. 

 The neck of the funnel was inserted in a test tube and the 

 entire apparatus attached to a ring stand. The fleas when 

 emerging would jump about and fall into the test tube below. 

 where they could very easily be removed. 



PREPARATION OF FOOD. 



Blood was secured in large quantities, centrifuged, and after 

 the serum was removed, the red corpuscles were placed in an 

 incubator and allowed to dry. The crystals were placed in a 

 mortar and ground to a fine powder, and this formed the food 

 for most of the larvae. Rat feces were ground by the same 

 process and gave fairly good results, but far better results 

 were secured from the dry blood. Only one objection could be 

 found when dry blood was used, and this could easily be over- 

 come if one took care in distributing the food throughout the 

 cage, namely: When too much moisture was present in the 

 cage and the blood was not evenly distributed, the moisture 

 would turn the dried particles into a drop of blood, and upon 

 drying again would hold the larvae prisoners, thereby killing 

 many. Two conditions were found unfavorable when rat feces 

 were used: One, when too much moisture was present mould 

 would start to grow and soon the cage would be in an un- 

 healthy condition for larvae ; second, when feces became too 

 damp a certain amount of ammonia was given off, and this 

 would kill the larvae if the top of cage was not removed. 

 ( 'ages could not be left uncovered, for in the dark larvae 

 become quite active and could easily escape, due to the shallow- 

 ness of the petri dishes. Mutton cloth saturated with blond 

 was alsn tried but gave very poor results, so this and rat feces 

 were abandoned shortly after the original experiment^. When 



