471 
August, ’24] TIETZ: ARSENATE solubility in bees 
THE SOLUBILITY OF ARSENATE OF LEAD IN THE DIGESTIVE 
FLUIDS OF THE HONEY BEE 1 
(Apis niellifica ) 
By Harrison M. Tietz 
Abstract 
The purpose of this study was to find out how the solubility of arsenate of lead 
is increased by the action of the digestive fluids present in the alimentary tract of 
an insect. In making these determinations, the honey bee, Apis mellifica Linn., was 
taken as the insect and the solubility of arsenate of lead powder in water was taken 
as the unit of solubility. The conclusions drawn from this experiment are as follows, 
(1) The solubility of arsenate of lead does not seem to increase when the powder is 
acted upon by the fluids in the oesophagus. (2) The digestive secretions of the honey 
stomach and stomach render the poison at least one and one quarter times as soluble. 
(3) The action of the intestinal juices is to throw at least three and three quarters 
times as much of the powder in solution as would be dissolved by water alone. 
In order that a poison may be absorbed by the body and so cause 
death, it is necessary that it should be in a soluble form. When ar¬ 
senate of lead is taken into the alimentary tract of an insect, it is very 
insoluble. When we realize that the average arsenate of lead powder 
contains but 32% arsenic pentoxide, and that the insect consumes but a 
small quantity of the spray mixture, we can readily believe that the 
solubility must increase when the powder comes in contact with the 
digestive fluids in the alimentary tract, otherwise the quantity of ar¬ 
senic capable of assimilation would be so small that the insect would be 
unharmed by its presence in the blood. It is the aim of this paper to 
show that arsenate of lead becomes more soluble when acted upon by 
the digestive fluids. 
Before entering upon a discussion of methods and results, the writer 
wishes to state that his findings are merely indications of what may take 
place in the insect’s body. In the alimentary tract of the living animal, 
the percentage of solubility may be even greater than the percentages 
obtained from the writer’s experiments. This is true for two reasons. 
In order to get a sufficient quantity of liquid with which to work, it 
was necessary to dilute the gastric fluids. The more concentrated diges¬ 
tive fluid, to be found in the living animal, may have the power to throw 
more of the arsenate of lead in solution. Another factor to be considered 
is that the alimentary tract while it remains in the living insect may 
continue to secrete gastric fluids and so produce larger quantities of the 
solvent resulting in more arsenate of lead being dissolved. When, how- 
contribution from the Entomological Laboratory of the Mass. Agricultural 
College, Amherst, Mass. 
