- 514 - 
Observations carried out "by means of a staining technique using 
toluidine "blue revealed histological changes in the nerve ganglia 
killed by pyre thrum that did not occur in individuals killed oj de- 
capitation or by nicotine sulphate or lead arsenate. 
CAMPBELL, F. I., SULLIVAN, ff. N., SMITH, L. I., and HALLER, H. L. (2177) 
1954. INSSCTICIDAL TESTS OF SYNTHETIC ORGANIC COMPOUNDS — CHIEFLY IZ 
OF SULFUR COMPOUNDS AGAINST CULICI1TE MOSQUITO LARVAE. Jour. Scon. E: 
27: 1175-1185. 
Of 68 synthetic organic compounds 24 were found to equal or 
exceed nicotine in effectiveness against mosquito larvae. Diphenylene 
oxide and diphenylene sulphide were the most effective of these com- 
pounds, killing nearly 100 percent of the larvae in 5 hours at 1 to 
200, 000 . 
LEVINE, N. D., and RICHARDSON, C. H- (2178) 
1934. THE SYNERGISTIC EFFECT OF THE CHLORIDES AID BICARB ONATES OF 
POTASSIUM AND SODIUM UPON THE PARALYTIC ACTION OF NICOTINE IN THE 
COCKROACH. Jour. Econ. Ent . 27: 1170-1175, illus. 
Nicotine produced a distinctly greater paralytic activity in 
0.1 M potassium chloride solution at lower concentrations of the alkal 
than in solutions of any of the other salts used, effects being 
noticeable at nicotine concentrations of 0.0004, 0.0003, and 0.0002 
percent. The American roach ( Periplaneta americana L.) was used. 
RICHARDSON, C. H., GLOVER, L. H., and ELLISON, L. 0. (0179) 
1934. PENETRATION OE GASEOUS PYRIDINE, PIPERIDINE AID NICOTINE INTO Tl 
BODIES OF CERTAIN INSECTS. Science 80 (2064): 75-77. 
In this preliminary report the insects were exposed to appro xims 
maximum vapor concentrations of the compounds in air at 30° C>, the ex - 
posurc times being varied as desired. T7hen entire insects were subject 
to the vapors, more nicotine in rag. per g. of tissue was found in the 
cuticula than in the entire insects. 
To prove that these toxic gases do not necessarily first enter 
the body through the spiracles, pass from the tracheae to the blood, 
and then enter the cuticula from the blood, special tests were made 
with larvae of com ear worms ( Heliothis obsoleta Fab.), cockroaches 
(p eriplaneta americana L.), and grasshoppers ( L'elar.oplus femur- rub rum 
DeG.) by exposing parts of their legs, wings, and abdomens to the 
vapors for 120 minutes. 
The results of these tests leave little doubt that these organi 
bases in gaseous condition passed directly through the cuticula of 
the insects. 
