8 BULLETIN 1160, U. S. DEPARTMENT OF AGRICULTURE. 
lowest for the compounds used in this study. The reduction of 
nicotine to hexahydronicotine results in greatly lowered toxicity. 
The hydrochloride of coniine (alpha n-propyl piperidine) is probably 
toxic at approximately 1 per cent. Atropine sulphate, because of its 
large molecule, gives a lower molar toxic concentration than its con- 
centration in grams per 100 cubic centimeters would suggest. 
The outstanding results for the group containing amines, amides, 
and similar compounds are the pronounced toxicities of certain 
methylamine, ethylamine, and alkyl ammonium compounds. The 
methylamine compounds are more toxic than the corresponding ethyl- 
amines. It is to be further noted that of the methyl derivatives, 
the trimethyl and tetramethyl are most effective. The increased 
toxicity of benzylamine as compared with aniline is interesting. The. 
plant tolerance for these compounds is generally low. 
The aldehydes and ketones, with the exception of benzaldehyde, 
are practically without effect on either insect or plant. 
With the exception of capryl alcohol, the aliphatic alcohols have 
little toxic value. Benzyl alcohol, a cyclic compound, is moderately 
toxic. 
U. S. P. cresol is more toxic than phenol and resorcinol. Pyrogallol 
shows little toxicity. 
The esters showed some toxicity to the insect and were harmful to 
the plant. 
The various sulphonic acids and their salts showed no appreciable 
toxicity to the aphids. Attention should be directed to the decreased 
toxicity of sodium phenol sulphonate (U. S. P.) as compared with 
phenol. Picric acid showed appreciable toxicity, but was quite 
injurious to the plant. The minimum toxic concentration of the fish- 
oil soap used in most of these experiments was about 6 grams per 100 
cubic centimeters; at 0.3 gram per 100 cubic centimeters, the con- 
centration used in these experiments, it killed an average of 14 per 
cent. 4 
The slight toxicity of the benzene series was found to increase from 
benzene through toluene to xylene. The plant tolerance, however, is 
low. 
Chloroform and carbon tetrachloride require about 30 grams per 
100 cubic centimeters for the lethal concentration. Plant tolerance 
was small. The substitution of chlorine into the benzene ring was 
found to increase toxicity. 
The essential and fixed oils showed some toxicity to both insect 
and pi ant. 
4 This figure has not been deducted from the toxicity values given in this paper. Since relative values 
are most important in an investigation of this nature, and, further, since 0.3 per cent fish-oil soap was used 
in most of these experiments, the deduction of the comparatively small soap toxicity is not considered 
essential. 
