166 Arsenic not injurious to Larves of Flies. 
21 XVIIL—On the power possessed by the Larves of various 
mon Flies of consuming, without apparent injury to them- 
rete the flesh of animals vie have died from the effects of 
Arsenic; by Frank H. Sro 
Read before the Boston Society of Natural History, January 5, 1859. 
Some months since my attention was attracted by — 
several living maggots upon the liver of a subject in the stom 
ach of which I had —— detected the presence of arsenic. 
This, eight days after death. As this liver was found, on analy- 
sis, to be saturated with arsenic, a number of experiments were 
made for the purpose of ascertaining whether the larvee observed 
had really been nourished by the poisoned flesh on which they 
ere discovered. 
Several living rats having been obtained, they were fed with 
eake which contained arsenious acid in various quantities, After 
eating this they in every case soon died. Their skins having 
n removed, the carcasses were exposed in a chamber to which 
flies had ive access, In the course of forty-eight hours the 
bodies of the rats were thoroughly fly-blown, and were soon 
covered by a multitude of larve. Having completel y consumed 
the flesh of the rats—leaving the bones bare, as in the specimen 
now exhibited to the Society—the maggots concealed themselves 
in sheltered corners and were converted into chrysalids in due 
course. These results were constant, having been exactly simi- 
lar in every instance, me two dozen or less of these chrysa- 
lids being subjected to analysis, metallic arsenic was readily ob- 
tained from them. It might be thought that this proves nothing 
more than that the flesh of the rats contained arsenic, and that, 
that obtained rear the shependide: had possibly been mechani- 
cally attached to the exterior surfaces of the larvee and not have 
‘ been swallowed by them. This view would indeed seem to be 
supported by the fact that—as may be seen in the specimen pre- 
sented—the surface of the bones from which the flesh has been 
a devoured is covered with a white powder which has the 
rance of arsenious acid. However this may be, only two 
BA ves remain if it is not admitted that the arsenic found 
in the chrysalids had really been assimilated by the larve: 
either the latter must possess an instinct which leads them to 
in which arsenic or other inorganic poison exists when contain 
in organic tissues, it seems idle to dwell at greater pn on 
this point. 
