318 JOURNAL OP ECONOMIC ENTOMOLOGY [Vol. 3 



does the gas cause sickness. In the entire three seasons' work this 

 occurred only five or six times. 



In the winter of 1907-1908 in fumigating over three thousand trees 

 eight hundred of which were large seedlings, two men quit work be- 

 cause the gas made them sick. These men operated the pulley ropes 

 which lifted the edge of the tent from the ground and raised it to 

 the top of the derrick. Just as soon as the edge of the tent is raised 

 the gas comes out and the men who operate the pullej' ropes being 

 nearest the opening get more of the gas than the other men. The trees 

 were very large, requiring from four to six pounds of cyanide. No 

 note was made as to whether or not the night was calm or on the con- 

 dition of the tents as to dampness which largely determines the 

 leakage of gas during exposure. 



Only one instance happened in the season of 1908-1909 in fumigat- 

 ing about a thousand trees. The night of January 11, 1909, was so 

 far as one could determine absolutely calm. The trees were fairly 

 large, requiring from two to four pounds of cyanide. We changed 

 the tents every 40 minutes. The tents being somewhat damp were 

 very tight so that little gas leaked out during the period of exposure. 

 Five men became sick on this night. One of these emptied the residue 

 from the crocks and held his head over the residue as it was being 

 poured out so that he breathed the escaping gas. This, of course, 

 was entirely unnecessary. The other four operated the pulley ropes 

 as did the men who became sick in the tests of 1907-1908. Two be- 

 came sick and were relieved by two others who also soon were affected. 



On this night I relieved one of the men operating the pulley ropes. 

 In a short time my heart beat much faster than the work seemed 

 to justify, then dizziness overcame me and I stretched out under an 

 orange tree. In about 5 minutes it became necessary to go to stool. 

 After this a nauseating feeling remained for some time followed by 

 chills and trembling of the muscles and almost total loss of muscular 

 strength. A vicious headache terminated these symptoms. These 

 symptoms were in the main common to all the affected persons. In 

 one or two instances vomiting occurred. 



In October, 1909, we, were fumigating some trees about ten feet in 

 height, using a 25 per cent increase over the dosage given in Bulletin 

 76 of the Bureau of Entomology and moving the tents every 25 min- 

 utes. The shortness of the exposure gave little time for the gas to 

 leak out and also the tents were much tighter than those used on 

 former occasions. There was no breeze. During the first night no 

 one became sick although the gas was very strong. However, dur- 

 ing the second night all of us got sick. One man fell over and the 



