38 
Psyche 
[June-Sept. 
between the introduction of the insect into the jar and this 
point constituted the time necessary to produce death. 
The stock solution of trimethylamine had a concentration 
of 33 % . It is doubtful if a greater concentration than this 
ever occurs in nature. Dilutions of the stock solution with 
water were used for the remaining tests. 
By making a few progressive records of the action of the 
chemical on the beetles, paralysis was found to occur in the 
following order : 
1. Paralysis of posterior legs. 
2. Paralysis of middle legs. 
3. Paralysis of anterior legs. (This followed so closely 
upon that of the middle legs that in concentrated atmos- 
pheres the time interval could not be determined.) 
4. Paralysis of antennse. 
5. Paralysis of mouth-parts (practically all at once). 
6. Spasmodic twitching of tarsi and tip of abdomen. 
7. Slow movements of legs and head. 
8. Movement of abdomen only. (May continue for many 
hours.) 
9. All movement ceases. 
The time durations necessary to bring about death at 
various concentrations of trimethylamine were as follows: 
33% — 5 minutes 10% — 22 minutes 
25% — 7 minutes 5% — 40 minutes 
20% — 10 minutes T% — 70 minutes 
Fig. 1. Toxicity of trimethylamine for Necrophorus orbicollis. 
