EXPERIMENTS WITH PTBETHBUM. 17 



3.00.— Still no change. 



September 22,9.30 a.m. — No motion left except a very Blight a 

 sional twitching of the anterior proh 



2. PARALLEL EXPERIMENT IN OPEN AIR. 



September 20, 11.45 a. m. — A larva similar in all the pre- 



ceding was dusted in the same maimer with the same powder, in the 

 same quantity, at the same time. 



In 10 minutes it began to show signs of uneasiness. In 13 mil, 

 began to struggle. The spasms increased in violence until 12.50 when 

 they began to subside. There were still strong writhings at 3.30, and 

 the body had only just begun to contract; while the confined worms 

 had reached a similar condition at 12.30. 



At 9 a. m.. September 21, the body had shrunken enormously, but 

 there was still motion of the entire body. 



3.30 p. m. — No perceptible clian_ 



September 22, 9.30a. m. — Dead. This seems strange in view of the 

 fact that the confined larva- which were strongly inrluencedby the pow- 

 der at a much earlier period are still alive. 



EXPERIMENTS 3 AND 4. 



The following experiments were made with nine samples of powder : 

 1st, the ordinary powder sold by Cutler Bros. & Co., of Boston, next, 

 five samples labeled Cutler Bros. Xo. 1, No. 2, No. 3. Xo. I. and H 

 sent to the Department for comparative test : 7th. pyrethrum imported 

 by Lehn & Fink, of Xew York City, in 1881 : 8th, the 1882 importation 

 of the same firm : and 3 9th, a powder made from flowers raised by Pro- 

 fessor Eiley in 1882. 



In experiment 3. six young larva- of Hyphantria textor, about one- 

 fourth grown, were placed in each of nine labeled, closed tin 1 

 (11x8.5x3.5 cm.), and a small quantity of each sample of powder was 

 dusted on the dorsum of the anterior abdominal segments of the worms 

 in each box. 



In experiment -1. three half-grown larvae of the same insect were used 

 in the same boxes and da -ted in the same manner. Bach worm received, 

 as nearly as could be judged by the eye. the same quantity of the pow- 

 der. 



5135 j 



