THE CANADIAN ENTOMOLOGIST, . 343 



enumerated above about four or five hours to do this, so that we should 

 begin about i p.m. As a matter of fact, the time varied considerably 

 owing to unforeseen additional labour. When everything is ready two men 

 go to the top floor, and beginning at one end of the hall, pass into 

 opposite rooms, one man on each side of the hall, gather the edges of the 

 newspaper in the fingers and pour the cyanide directly into the acid and 

 water and walk quickly out of the room, closing the door after them. 

 There is not the slightest danger, apparently, in pouring the cyanide 

 directly into the acid and water if one does it coolly and quickly and holds 

 the breath for a few seconds until the door is reached. Of course, the 

 chemical reaction is very rapid and begins immediately, but by reaching 

 the hand out over the bowl and turning the head a little away and holding 

 the breath a few seconds we have never in all of our work — and we have 

 always done it that way — experienced the slightest annoyance from the 

 gas. By passing rapidly down the hall from room to room and floor to 

 floor two men will set the whole 50 rooms off in ten or fifteen minutes. 



Our .success last year was very gratifying indeed, although we had 

 some complaints of bedbugs in a few rooms late in the session. This, in 

 most instances, could be traced to some old wooden bedsteads that had 

 not been fumigated, and which I supposed were to be thrown out and 

 destroyed, but which were used afterwards by students who, coming late 

 in the session and finding these old bedsteads, utilized them instead of 

 buying new ones. In a few cases I believe it was due to the large cracks 

 around the doors, through which the gas dissipated itself into the halls. 

 To obviate this difficulty, we tried a plan this year that seemed to work 

 very well, and, I believe, will prove more effective. 



Instead of caulking all the rooms in a division we simply caulked the 

 rooms on the top floor of that division first and then fumigated them at 

 once. As the fumigator would close the door of a room two men, who 

 stood ready with water-soaked strips of paper, would quickly seal the 

 cracks around the edges of the door and the keyhole. These two men 

 would caulk a door in less than two minutes, and the rooms must have 

 been made as tight as is possible under average conditions. All of the 

 rooms on that floor were treated in this way, after which the force passed 

 to the floors below in succession, treating each in the same manner. 



