32 
Mr. Smith asked whether the characters of the genitalia are constant, 
Mr. Atkinson replied that they are within generic limits, but that they 
do not differ with species except as regards the distance from the anal 
end of the body to the genitalia. Mr. Atkinson further stated that he 
thinks that these Nematodes reach the leaves by being borne up in the 
axils of the leaves as the plants grow. 
Mr. Riley asked whether it was not possible that the young might 
-work their way up the plants to the leaves during rain. 
Mr. Atkinson agreed as to the possibility of this method, and further 
stated that he had received what he supposed to be the Tylenchus 
tritict or scandens of Europe, from grass in Colorado. 
Mr. Riley read the following paper: 
KEROSENE EMULSION AND PYRETHRUM. 
By C. V. RILEY, Washington, D. C. 
In the Rural New Yorker of June 20, 1891, Dr. Albert E. Menke, 
director of the Arkansas Experiment Station, criticises a review of Bul- 
letin No. 15 of his station, published in InsEcT Lire. The principal 
point raised by Dr. Menke is that kerosene extract of pyrethrum, made 
intoan emulsion with soap and water, is entirely different from an ague- 
ous extract of pyrethrum made into an emulsion with soap and kerosene, 
as recommended by Professor Gillette. He also disputes the statement 
that the idea of combining kerosene and pyrethrum was given him by | 
Prof. Jerome McNeill.* Professor McNeill has experimented with both 
the Gillette and the Menke combinations, and in a recent communica- 
tion he confirms the statement that he first suggested the combination 
of these two substances to Dr. Menke and gives the results of his expe- 
rience as follows: 
In preparing, in accordance with your directions, Dr. Menke’s mixture, I used the 
proportions given in Bulletin No. 15 of the Arkansas Station. The extract of pyre- 
thrum was made by simply digesting the powder in kerosene for three or four hours. 
The resulting emulsion is good, and it is about as effective on the Cabbage Worm as 
he claimed it to be on the Cotton Worm. Mr. Gillette’s mixture I made with the 
same proportion of soap, kerosene, and pyrethrum as the first mixture contained. 
* *« * The emulsion was made in the usual manner, and then it was diluted with © 
the kerosene tea. When Dr. Menke’s mixture was diluted equally, there was no dif- 
ference between the two in appearance or odor. In using dilutions of the same 
strength fewer worms survived the application of Mr. Gillette’s solution, but the dif- 
ference was immaterial, as, when I applied the mixture without knowing which I 
was using, I could not always tell which of the two I had employed. Such in brief 
are the conclusions I have reached after a considerable number of experiments with 
the two. I shall not be satisfied, however, without further trial of these mixtures 
upon different worms. One thing that has disturbed my satisfaction with these ex- 
* An error was made in the proportions of veratrin given in INSEcr LIFE, in that 
one-fourth pound was written instead of one-fourth ounce. Three lines above this 
error, however, the correct proportions are mentioned, which is sufficient evidence 
that the error was a clerical one, 
