88 MOSQUITOES 



suggesting that possibly a mutton chop might help matters 

 along. 



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

 into each of five experiment jars. The next day I could give only 

 a casual glance before going out of town, and this showed noth- 

 ing unusual ; l)ut the day after, March 26th, when I reached the 

 laboratory at 8 a.m. I saw at once that something was wi-ong, be- 

 cause all the living larva? were at the surface, head down, spira- 

 cles reaching the air. In every jar into which I had placed the 

 meat I noted the same appearance, and I hastily fished out every 

 particle. But it was too late : more than half were already 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 February was left unharmed, 

 and this was placed on the water-bath March 26th. 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 larvae.* Vegetable decay and the harder refuse from 

 insect bodies will help along the development ; Init beyond that 

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

 condition of the water may very largely determine the frequency 

 with which the supply of oxygen must be 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 be exactly duplicated. 

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

 ture, the breathing habits are quite different and the insects ob- 

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



* This generalization is much too broad. The larva^ of Culex impiger, 

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

 and so, possibly, will larva? of certain other species of Culex.— L. O. H. 



