378 
Journal of Agricultural Research 
Vol. IX, No. ii 
became thick and pastelike. By placing cephalin under a small bell jar, 
the air of which remained saturated with benzene, it absorbed benzene 
from the air until finally a liquid mass was produced. The same was 
true for toluene and xylene. This shows that cephalin and either ben¬ 
zene, toluene, or xylene are miscible in all proportions. On the other 
hand, brombenzene, with a boiling point of 150° C., dissolved but one 
capsule in 1 c. c. Benzaldehyde (165° C.) slowly penetrated the cephalin, 
but dissolved but little of it; while anilin (170.5 0 C.) salicylic aldehyde 
(185° C.), nitrobenzene (200° C.), and nitroxylene (240° C.) did not 
penetrate the cephalin and dissolved but very slight traces of it. Five 
c. c. of nitrobenzene, evaporated to dryness, left a very slight greasy 
mark on the evaporating dish. An effort was made to extract cephalin 
from the brain tissue with nitrobenzene without success. Lanolin also 
is practically insoluble in nitrobenzene. One c. c. of benzene containing 
0.16 c. c. of cephalin was poured into 10 c. c. of nitrobenzene and the 
mixture blown with an electric fan until the benzene was evaporated, 
resulting in the cep halin’s being thrown out of solution. From these 
results it appears that compounds with high boiling points are poor 
lipoid solvents, but are the most toxic to insects. These experiments 
would indicate that an increase in lipoid solubility as determined by the 
above method causes a decrease in toxicity in the chemicals used. Fur¬ 
ther work is now in progress to determine whether a similar relationship 
exists between the boiling point, lipoid solubility, and toxicity of a wider 
range of chemicals from the alipathic series and the terpenes. 
TOXICITY OF BENZENE DERIVATIVES TO OTHER INSECTS 
The toxicity of the benzene derivatives was found to be similar for 
other insects, and although this work has not been completed, one point 
may be noted. A comparison of the bluebottle fly {Lvcilia sericata Mg.) 
with the house fly (Musca domestica L.) shows that house flies die more 
quickly from compounds with a low boiling point than bluebottle flies, 
while compounds with a high boiling point are more toxic to the blue¬ 
bottle flies than to the house fly. Similarly, the cockroach ( Blatella ger - 
manica Linn.) succumbs less readily than the potato beetle (Leptinotarsa 
decemlineata Say) to low boiling compounds and more readily to high 
boiling compounds. This relationship may be due to morphological 
differences in the insects, possibly the diameter of the spiracles or trachea. 
CONCLUSIONS 
Although no effort has yet been made to apply the results, certain pos¬ 
sibilities are apparent. Even if the compounds with low boiling points 
are less toxic than those with high boiling points, inasmuch as more of 
such compounds may be evaporated before saturation is reached, better 
results may be obtained. This is shown in figure 4, which gives the 
maximum amount (in pounds) that will evaporate in 1,000 cubic feet of 
