Action of Drugs upon Nervous System of Insects 175 



81 (2041) 



Action of drugs upon the central nervous system of insects. 



By G. F. PILZ and W. J. CROZIER. 



[Front the Zoological Laboratory, Rutgers College, New Bruns- 

 wick, N. J.] 



Peculiarities revealed by study of the action of neurophil drugs 

 in lepidopterous larvae 1,2 led to an extension of the observations 

 to include an imaginal insect. Effects following injection of 

 solutions of drugs into the thorax of grasshoppers were com- 

 pared with those attending the direct application of these sub- 

 stances to the thoracic ganglia (exposed by removal of the ventral 

 thoracic sclerites). In all essentials, the two methods gave 

 comparable results. 



As in caterpillars, strychnine produces momentary general ex- 

 citation, but only when present in very high concentration; it 

 fails to induce "reversal of inhibition." In the grasshopper, 

 however, such "reversal" appears after administration of nico- 

 tine or of camphor. The legs are thrown outward and upward 

 if (under nicotine) the abdomen or a femur be touched, and 

 (under camphor) when the mouth-parts are stimulated tactically. 

 The grasshopper normally clasps a stimulating object if, as in 

 these tests, the animal be held by a clip fastened upon the wing- 

 covers. Nicotine, and pilocarpine, stimulate especially move- 

 ments of the two posterior pairs of legs, while under camphor 

 all three pairs and the mouthparts undergo spasmodic move- 

 ments. 



Grasshoppers, caterpillars, and crayfish 3 agree in presenting 

 definite evidence of neuronic excitation by these substances : 

 strychnine, pilocarpine, picrotoxin, nicotine, veratrine, atropine, 

 caffeine, camphor, phenol. To this general correspondence there 

 may be added certain aspects of detailed agreement. These 

 arthropods differ pronouncedly from the earthworm in the fact 

 that, with the latter, 4 nicotine, caffeine and phenol fail to pro- 



1 Crozier, W. J., Proc. Soc. Exp. Biol, and Med., 1922, xix, 326. 



2 Crozier, W. J., Biol. Bull, 1922, xliii, 239. 



3 Moore, A. R., Proc. Soc. Exp. Biol, and Med., 1922, xix, 335. 



4 Moore, A. R., Jour. Gen. Physiol., 1921, iv, 29. 



