58 
ypsect in all its phases may be instantly killed by contact with minute quantities of 
permanganate of potash. It is claimed that 1 part of this substance in 1,500 of 
solution distributed in mosquito marshes will render the development of larve 
impossible; that a handful of permanganate will oxidize a 10-acre swamp, kill its 
embryo insects, and keep it free from organic matter for thirty days, at a cost of 25 
cents; that with care a whole State may be kept free of insect pests at a small cost. 
An efficacious method is to scatter a few crystals widely apart. A single pinch of 
permanganate has killed all the germs in a 1,000-gallon tank. 
The item is so obviously ridiculous upon its face that it would hardly 
seem worth while to make any attempx to refute its statements. Ney- 
ertheless, it has been so widely read that definite experimentation 
seems necessary to set the matter at rest. The unknown author’s 
ignorance of the life history of mosquitoes in the opening sentence 
need not necessarily imply that he would not know a good remedy if 
he found one. Careful experiments were undertaken by the writer 
in July, 1898, with various strengths of permanganate of potash in 
water containing mosquito larve from one to six days old. It was 
found that small amounts of the chemical had no effect whatever upon 
the larvee, which were, however, killed by using amounts so large that, 
instead of using a ‘‘ handful to a 10-acre swamp,” at least a wagon 
load would have to be used to accomplish any result. Moreover, after 
the use of this large amount and after the larve were killed, the same 
water twenty-four hours later, sustained freshly-hatched mosquito 
larvee perfectly, so that even were a person to go to the prohibitive 
expense of killmg mosquito larve in the swamp with permanganate 
of potash, the same task would have to be done over again two days 
later. 
The same conclusion was subsequently reached, after careful experi- 
ment, by Dr. Lederle, of the New York health office, and by the Ital- 
ians Celli and Casagrandi. 3 
Proprietary miatures.—A namber of proprietary and secret mix- 
tures recommended for mosquito-breeding pools and which have been 
put on the market since the wide-spread interest in the mosquito ques- 
tion has sprung up have been tested by the writer, but none have been 
found more satisfactory than the cheapest petroleum oil. 
Fixperiments of Celli and Casagrand:.—The most extensive series of 
experiments with culicidal mixtures which has been made was con- 
ducted by the Italians Celli and Casagrandi, above referred to. They 
have tabulated in the ‘‘Annali d’ Igiene Sperimentale, Rome (Vol. IX, 
Fase. II], 1899, pp. 317-353), the results of experiments with many 
substances. Referring to petroleum, they say that apart from the 
question of the expense, which outside of America is worthy of note, 
the action of petroleum in destroying mosquito larve is not always to 
be put in the front rank. Their conclusions are practically as follows: 
(1) Of the whole period of the cycle of development. of mosquitoes the stages in 
which they are most easily destroyed are those of larvee and of the aerial mosquito, 
and larvee are most easily killed the younger they are. 
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