88 MOSQUITOES 



suggesting that possibly a mutton chop might help matters 

 along. 



On March 24th, I put a small lump of raw Ijeef chopped fine, 

 into eacli of live experiment jars. The next day I could give only 

 a casual glance before going out of town, and thi.s showed noth- 

 ing unusual ; but the day after, March 2()th, when I reached the 

 lai)oratory at 8 A.M. I saw at once that something was wrong, lie- 

 cause all the living larva- were at tlie surface, lie.ul down, s])ira- 

 cles reaching the air. In every jar into which 1 had jilaced the 

 meat I noted the same apiiearance, and 1 hastily fished out every 

 particle. But it was too late : more than half were alreatly dead, 

 others seemed to show fungoid growth proceeding from the seg- 

 ments, so, to prevent their dying, I killed them off with a dose of 

 formalin. One large jar received in Fel)ruary was left unharmed, 

 and this was placed on the water-bath Marcli 2Gth. Nothing has 

 come from it at the date of present writing, and nothing may ever 

 come from it, but its history must be written later. 



But this experiment, fatal as it proved, was of some value. It 

 shows that water too foul with animal decay is not suitable for 

 mosquito larv;p.* Vegetable decay and the harder refuse from 

 insect Ixxhes will help along the development ; but beyond that 

 the water must be clean. It seems to indicate further that the 

 conditi(»n of the water may very largely determine the frequency 

 with which the supply of oxygen nnist I )e renewed from above the 

 surface. In June, with a supply of water at a relatively high 

 temperature in which microscopic life is swarming, I have no 

 doubt Dr. Howard's observations would i)e exactly dtq)licated. 

 With the same species in clear water, at relatively low tempera- 

 ture, the breathing habits are quite d liferent and the insects ob- 

 tain, I have no doubt, a goodly portion of their oxygen from the 



* This generalization is nuicli (oo bread. The larva' of Culcr impiger, 

 for example, will swarm in water foul wilii decomposing animal matter, 

 and so, possibly, will larvfp of certain other species of Culcx.— !>. O. 11. 



