18 BULLETIN 1023, U. S. DEPARTMENT OF AGRICULTURE. 



Ground squirrels (Citellus richardsoni) are about four or five 

 times more sensitive to strychnine administered subcutaneously than 

 rats. This helps to account for the comparative difficulty in poison- 

 ing rats. 



The percentage of strychnine which would make a successful rat 

 bait can not be stated at present. After the factors of rapid con- 

 sumption and palatability are solved, it should be possible to obtain 

 good results with 0.75 per cent of the alkaloid in potent form in the 

 formula. This percentage represents three times the fairly certain 

 fatal dose in a meal of the average size. It is probable that any 

 success obtained with lower concentrations represents instances of 

 fatalities from amounts smaller than can always be considered cer- 

 tain or from larger amounts of bait than can always be relied upon 

 to be eaten. Experiments herein represented should be continued, 

 employing feeding tests with perfectly palatable strychnine baits, in 

 order to determine how rapidly strychnine is absorbed from the 

 particular bait. iSince the absorption may be very rapid, an in- 

 crease in the percentage of strychnine here given may be found 

 expedient, even though the bait is eaten fairly rapidly. 



LITERATURE CITED. 



(1) Allard, Ed. Die Stryehninvergiftung. In Vierteljahr. ger. Med., 25, 



suppl. (1903) : 234-329. 



(2) Bert, Paul. Note sur la resistance considerable que presentent les ani- 



maux nouveaunes a Taction de certains poisons. In Gaz. med. 

 Paris, 25 (1870) : 145. 



(3) Boelter, W. R. The rat problem, p. 123. London, 1909. 



(4) Cutler, E. C, and Alton, B. H. The control of strychnine convulsions by 



intraspinal injections of magnesium sulphate. In J. Exp. Med., 

 25 (1917) : 83-92. 



(5) Falck, Ferd. Aug. Ueber den Einfluss des Alters auf die Wirkung des 



Strychnins. In Arch. ges. Physiol., 34 (1884) : 530. 



(6) Ueber den Einfluss des Alters auf die Wirkung des Strych- 

 nins. In Arch. ges. Physiol., 36 (1885) : 285. 



(7) Githens, T. S. The influence of temperature on the action of strychnine 

 in frogs. In J. Exp. Med., 18 (1913) : 300. 



(8) and Meltzer, S. J. The control of strychnine poisoning by 



means of intratracheal insufflation and ether. In J. Pharmacol., 2 

 (1910) : 357. 



(9) Hale, Worth. Studies in tolerance, No. II — Strychnine, In J. Phar- 

 macol., 1 (1909) : 39. 



(10) Hare, Hobart A. Studies on the influence of strychnine on the spinal cord 



of rabbits. In Am. J. Physiol., 5 (1901) : 333. 



(11) Hatcher, Robert A., and Eggleston, Cary. The fate of strychnine in the 



body. In J. Pharmacol., 10 (1917) : 281. 



(12) Hunt, Reid, and Seidell, Atherton. Studies on the thyroid, I — The 



relation of iodine to the physiological activity of thyroid prepara- 

 tions. U. S. Hygienic Lab. Bull. 47 (1908) : 21. 



(13) Knowlton, F. P., and Moore, A. R. Note on the reversal of the reciprocal 



inhibition in the earthworm. In Am. J. Physiol., 44 (1917) : 490. 



