II 



This mortality cannot be attributed entirely to poisoning. It is rea- 

 sonable to assume that part of these were killed mechanically or died of 

 other causes. To determine which of the dead were poisoned, chemical 

 analyses were made. After the bees were collected from the cages they 

 were taken to the laboratory and treated with one-tenth normal sodium 

 hydroxide, heated to boiling; then enough nitric acid was added to make 

 the solution acid, and this boiled two minutes, washed five times with 

 distilled water, and dried in the oven.^ This treatment was for the pur- 

 pose of removing any arsenic that might be on the surface of the bee. 

 Individuals were then taken from the various lots and analyzed according 

 to the Gutzeit method for determining small amounts of arsenic. The 

 records are shown in Tables III and IV. 



Table IV. — Showing Positive and Negative Tests for Arsenic Obtained 



From Examination pf 216 Bees From the Dusted Tree. Each 



Bee Is Represented by * or .0, the * Indicating a 



Positive Test and the o a Negative Test 



1 See note 3, page 9. 



