168 Arsenic not injurious to Larves of Flies. 
should have perished by scores, as they did while depositing 
their eggs upon the poisoned flesh. Im may here observe that the 
only reference to this subject which I have been able to find is 
the remark of Jaeger (quoted by Orfila, Trait? de Toaicologe, 
Paris, 1852, I, 379) that “insects, such as spiders, flies, &c., 
quickly die when arsenious acid in solution is introduced into 
their digestive organs applied to their soft exterior parts. 
The larvee of flies a a little longer than the insects which have un- 
dergone metamo $ 
It being imposible: to obtain satisfactory results by the method 
of experimenting which has just been desc “ote I had:com- 
menced another series of experiments upon mall animals, into 
the arterial systems of which solutions of arsenic of different 
degrees of concentration had been injected soon after death. 
ese trials were brought to an abrupt termination by cold 
—— and the consequent dieappearence of all flies. The 
e difficulties were however experienced here as in the pre- 
ot cases ea in a lesser cae the flesh having always 
a tendency to become dry and hard. As this hardening did 
not take place so rapidly in the injected specimens as where bits 
of flesh had been soaked in a solution of arsenious acid, so the 
larvee were enabled to attain a much larger size, before drying 
_ up, than in the previous instances. Indeed in several cases 
where favorable, moist positions had been secured, they lived 
for three or four days, becoming quite large and evidently almost 
ready to pass into the chrysalid state. This, upon the body of 
a rat weighing seven and a half ounces, into which four and a 
alf 8 aaa of arsenious acid in aqueous solution had been in- 
ject 
In order to avoid the esha influence of arsenious acid, 
solutions of arsenic acid—an eminently hygroscopic eon 
—were resorted to, but from having been used in too concen- 
trated a state, the larvae were destro ed, in the course of, a few 
hours after birth, from contact with the solution which had 
out upon ‘the surface of the flesh; showing clearly, as 
with arsenious acid, om there i is a limit to the amount of arsenic 
which these larvee can s 
It is probable faded that in every case the harmlessness of 
the poison eee <8 on its being so much diluted that it 
can oe me ce rec any flesh into which arsenic has 
been carri no Bs A view which is certainly 
soggy 8 one oy the fact t of finding them upon the arsenl- 
human liver, an veka ae as is well known, is suscep- 
poison. 
thle of — @ particular. ly large quantity of this 
