io8 
Journal of Agricultural Research 
Vol. VII, No. 3 
and since the tissues were fixed with absolute alcohol, which must have 
passed into the bees chiefly through the mouths and anal openings, the 
cells in the epithelial lining of the alimentary canal were not well pre¬ 
served, so they have been drawn diagrammatically in outline from 
Snodgrass (22). In sections through the middle of the ventriculus, the 
“ precipitate ” is arranged more or less in concentric circles (Pi. 2, fig. J, 
pr ). This arrangement is probably caused by the peritrophic mem¬ 
branes being likewise arranged. In the lumen (/) and between the con¬ 
centric circles of *‘ precipitate” the “precipitated” particles are scattered 
irregularly. In Plate 2, figure J, the epithelial ( ep) and muscular (m) 
walls have been drawn diagrammatically, showing how the stain proba¬ 
bly passes through these walls into the blood where most of it is taken up 
by the Malpighian tubules. The other parts of this figure were drawn 
with the aid of a camera lucida. 
Since no blue “precipitate” was observed in the epithelium (PI. 2, fig. 
F, ep) of the small intestine, it seems that the stain did not pass through 
the walls of this organ, although “precipitate” was easily seen in the 
lumen (/) of the small intestine. Most of the “precipitate” usually 
occurred in large particles near the center of the lumen, while the inner 
wall of the epithelium was often lined with a layer of “precipitate” 
composed of innumerable small particles. 
Despite the fragmentary sections of the rectum, a careful study was 
made of this organ, but no blue “precipitate” was seen in its walls; 
nevertheless it was quite conspicuous in its lumen (PI. 2, fig. I, /). In 
the rectum, as well as in the other parts of the alimentary canal, there 
was considerable “precipitated” material which was not stained. This 
and the pollen grains were easily distinguished from the “precipitated” 
indigo-carmine by the blue color of the latter. 
The preceding results obtained in tracing nicotine as a stomach poison 
by means of “precipitating” indigo-carmine is not meant to be conclu¬ 
sive, but merely to point out the possibilities for future investigations 
along this line. For these results to be conclusive, the nicotine should 
have been traced without the aid of a stain like indigo-carmine; buf 
owing to the odor from this insecticide bees can not be forced to eat 
food containing a large quantity of nicotine. For this reason it did 
not seem possible in preliminary work of this nature to be able to trace 
an extremely small amount of nicotine without using some compara¬ 
tively harmless stain with it. 
In passing through the walls of the ventriculus, it is scarcely possible 
that the nicotine and indigo-carmine were separated from one another, 
and the experiments on page 91 show that nicotine as a stomach 
poison kills by paralysis. It must therefore be concluded that nicotine 
in passing through the walls of the ventriculus is not so materially 
changed as to destroy its effectiveness. That all the tissues, even in¬ 
cluding the brain, were stained more or less with the indigo-carmine 
