1936] Toxicity of Trimethylamine for N ecrophorus 37 
THE TOXICITY OF TRIMETHYLAMINE FOR 
NECROPHORUS ORBICOLLIS (SAY). 
By Cyril E. Abbott 
Morgan Park, 111. 
As a natural decomposition product of flesh, trimethyl- 
amine [N(CH 3 ) 3 ], is found, in varying concentrations, in 
those animal remains to which various necrophilous beetles 
are attracted. It is of some interest to know, then, how well 
a species such as N ecrophorus orbicollis can withstand the 
toxic effects of this chemical. 
For testing the resistance of the beetle to various concen- 
trations of the substance a glass jar with a hollow, ground- 
glass stopper was used. The jar had a capacity of 125 cc. ; 
the hollow in the stopper 5 cc. The stopper was stuffed 
tightly with cotton, which was then soaked with all the solu- 
tion it would contain without dripping. The jar was cleaned 
with hot water, the stopper replaced, and the whole allowed 
to stand for 1 minute before the specimen was introduced. 
The beetle was thus exposed to the chemical in its gaseous 
form. 
The insects used were active adults, and, although but 
one specimen was used at a time, each experiment was 
repeated with two additional beetles, so that an average 
could be determined ; this was necessary because individuals 
varied in size. The data on any specimen showing an unusu- 
ally long or short period, as compared with the other two 
specimens, was discarded; the average then being taken 
from the two remaining. 
It is somewhat difficult to determine the exact death- 
point for the Necrophori. Preliminary experiments indi- 
cated that although parts of the body may move for hours, 
beetles in which not more than one tarsus twitched spas- 
modically never recovered after removal from the jar; this 
was considered the “death-point,” and the time elapsing 
