18 BULLETIN 1307, U. S. DEPARTMENT OF AGRICULTURE 
and the daily burning of all grades of mill waste in which seeds of 
such cotton might be found. A corps of inspectors was employed 
and, to insure the faithful following of regulations, frequent exam- 
inations were made at the mills where foreign cotton was used. In 
general, sympathetic cooperation was obtained. This was especially 
noticeable in the case of southern mills, the owners and managers 
of which seemed to realize the danger of introducing the pink boll- 
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 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 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 in- 
sects 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 a 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 Kural Organization of this 
department conducted a series of manufacturing tests with cotton 
w T hich 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 
the bleaching, dyeing, or mercerizing properties of the cotton (5). 
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 com- 
mercial scale to fumigate densely compressed bales of cotton and 
kill any insect which might be inside. 
On March 10, 19 10, 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 
in a remarkably short time and became available for use on the 
date mentioned. Two of these plants were erected in Boston and 
