18 BULLETIN 723, U. S. DEPARTMENT OF AGRICULTUEE. 



worm and complied with the orders and regnhitions of the Federal 

 Horticultural Board in the most hearty and public-spirited manner. 



In the experiments with vacuum fumigation of lint cotton con- 

 ducted b}' Mr. Sasscer, under the direction and with the advice of the 

 Federal Horticultural Board, tests were made with variations in the 

 dosage of cj^anid, the degi'ee of vacuum, the length of exposure, the 

 temperature, and also in the depth of penetration. Steel tubes 

 l^ointed 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 w^as performed the 

 insects w^ere 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 Eural 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 b}^ 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 clestrojdng any insect in the bales of lint were 

 determined, it was decided to acid 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 w^hich might be inside. 



On March 10, 1910, the fumigation of all bales of foreign cotton 

 arriving at the United States was required as a condition of entry. 

 Advance notice liad l)oen gi\'eTi to the importers and others con- 

 cerned. In spile of considerable difficulties in obtaining materials 

 and in working out mechanical problems, large plants were erected 



