1918] ECON-OMIC ZOOLOGY ENTOMOLOGY. 55 



0.21 mg. ; picted with cotton gloves and wiped, 0.08 to 0.18 mg. Rain and 



weather had considerable influence ; when picked in the ordinary manner the 

 residue per fruit decreased 75 per cent when fruit remained 75 to 91 da^s on 

 the trees as compared with fruit piclied 3 to 5 days after spraying. Four 

 mg. of AS2O3 was found to be the maximum amount that will adhere to the 

 fruit. With small fruits and vegetables picked before and after rains the 

 amount of residue recovered ranged as follows: Strawberries from 8.6 to 34^ 

 mg. per quart, currants from 6.8 to 10.2 mg. per quart, blackberries from 3.8 to 

 11.2 mg. per quart, cabbage from 43.5 to 51.4 mg. per head and lettuce from 1.6 

 to 10.6 mg. per head, the outer leaves being included. 



It is pointed out that the standard medicinal dose of arsenic (AsiOs) is from 

 2 to 5 mg. and the dangerous dose, 60 to 120 mg. Cooperative experiments car- 

 ried out at the University of Chicago have shown lead arsenate to be somewhat 

 soluble in human gastric juice, but probably less so than white arsenic (AsjOs). 



The results of feeding lead arsenate and white arsenic to guinea pigs are 

 reported. 



The evidence presented indicates that under ordinary conditions no apples 

 will reach flie consumer carrying such amounts of lead arsenate per fruit as will 

 cause fatal poisoning in a healthy human adult. Strawberries should not be 

 directly sprayed with lead arsenate after they have fully formed, nor should 

 blackberries after they have formed, and currants if so sprayed should be 

 washed. With cabbage and lettuce ready for market arsenate of lead should 

 not be applied except sparingly, and in that event the outer leaves should be 

 removed and the heads washed. 



In experiments to test the effect of the drip from sprayed trees on live stock 

 it was found that average drip from trees amounted to 11.2 per cent where the 

 spray material was applied with reasonable care. Calves were confined to plats 

 of grass carrying spray material directly applied at concentrations of 3, 6, 

 and 10 lbs. of lead arsenate paste to 50 gal. of water. Calves pastured on 7 

 successive plats sprayed at the rate of 3 lbs. to 50 gal. of water were not seri- 

 ously poisoned but failed to gain weight and showed some minor effects. 

 Those pastured on grass sprayed at concentrations of 6 : 50 developed definite 

 symptoms of serious poisoning, but when removed to grass containing no 

 poison they fuUy recovered. Two calves pastured on grass carrying concentra- 

 tions of 10 : 50 developed serious poisoning and one died, but the other recovered 

 when removed to grass containing no poison. 



Sheep were pastured on grass containing similar amounts of lead arsenate. 

 Those which consumed grass on 10 successive plats carrying arsenate of lead at 

 concentrations of 3 : 50 gave no evidence of serious poisoning ; those which con- 

 sumed grass on the 6 : 50 plats developed serious symptoms but fully recovered 

 on removal to unsprayed grass ; those on the 10 : 50 plats gave evidence of 

 serious poisoning, one dying, but another recovering after removal to grass 

 free from poison. Sheep pastured within a pen beneath sprayed trees showed 

 no evidence of serious poisoning when the spray material was used at the rate 

 of 3 : 50 or 6 : 50, even though large amounts of spray were applied, but when 

 the application was at the rate of 10 : 50 they showed definite symptoms but 

 recovered. 



Hens and young chicks confined in pens and pastured on grass carrying 

 arsenate of lead at concentrations of 3, 6, and 10 lbs. to 50 gal. of water devel- 

 oped no symptoms of serious poisoning, although fed on 10 successive plats 

 within a period of 56 days. 



Quassia extract as a contact insecticide, N. E. McIndoo and A. F. Sievebs 

 (U. S. Dept. Agr., Jour. Agr. Research, 10 (1917), No. 10, pp. 497-5S1, figs. S).— 



