18 BULLETIN 723, U. S. DEPARTMENT OF AGRICULTURE. 
worm and complied with the orders and regulations of the Federal 
Horticultural Board in the most hearty and public-spirited manner. 
In the experiments with vacuum fumigation of lint cotton con- 
ducted by Mr. Sasscer, under the direction and with the advice of the 
Federal Horticultural Board, tests were made with variations in the 
dosage of cyanid, the degree of vacuum, the length of exposure, the 
temperature, and also in the depth of penetration. Steel tubes 
pointed at one end were provided. These had perforations near the 
point and were sealed in such a manner as to be perfectly airtight at 
the other end. Insects were placed within them, and the tubes were 
then driven into the bales. After the experiment was performed the 
insects were removed for examination. In this way the exact effect 
of the fumigation under all varying conditions at different depths 
within the bales could be determined. At the same time chemical 
tests were made by the Bureau of Chemistry of this department to 
run parallel with the tests with insects. These chemical tests con- 
firmed the rapid penetration of the gas. 
As the result of a suggestion made following a conference of a 
committee of cotton manufacturers with the Federal Horticultural 
Board, the then Office of Markets and Rural Organization of this 
department conducted a series of manufacturing tests with cotton 
which had been fumigated with hydrocyanic-acid gas to determine 
whether the fumigation by this agent would cause any injury to 
cotton fibers. The results of these tests indicate that such fumiga- 
tion of cotton did not cause any deterioration of the cotton, either 
as to percentage of waste, spinning qualities, tensile strength, or 
bleaching, dyeing, or mercerizing properties of the cotton (3). 
In the first series of experiments various insects more or less re- 
lated to the pink bollworm, but which are native to the United States, 
were used. After the preliminary work was done and the probable 
requirements for destroying any insect in the bales of lint were 
determined, it was decided to add a series of experiments with the 
pink bollworm itself. For this purpose, under extreme caution to 
avoid escape, a number of insects were brought from the Hawaiian 
Islands. The results in all essential respects were similar to those 
that followed in the case of the insects treated previously. 
As the result of all of this work, which taxed the ingenuity of the 
investigators engaged in it, it was found feasible on a commercial 
scale to fumigate densely compressed bales of cotton and kill any 
insect which might be inside. 
On March 10, 1916, the fumigation of all bales of foreign cotton 
arriving at the United States was required as a condition of entry. 
Advance notice had been given to the importers and others con- 
cerned. In spite of considerable difficulties in obtaining materials 
and in working out mechanical problems, large plants were erected 
