TOXICITY OF STRYCHNINE TO THE RAT. 7 



can be applied. Cutler and Alton (4) also successfully treated 

 grown cats by the same method for exactly th^ minimum fatal dose 

 of strychnine. The time element renders the practical application 

 of this less favorable in adults than in infants. The use of mag- 

 nesium sulphate is accompanied with some danger, which also pre- 

 cludes the use of this procedure unless previous experience in its 

 application has been had. 



EXPERIMENTAL PROCEDURE. 



Throughout the course of this investigation strychnine has been 

 considered from the angle of comparative pharmacology, the reason 

 being that at some future time this drug may be more widely em- 

 ployed in poisoning animals than at present. Moreover, the rela- 

 tion of one species to another offers a more tangible basis for illustra- 

 tion than abstract data representing the lethal dose for rats. At the 

 same time this is a very suitable plan from the aspect of the drug 

 itself in that it has been used extensively as an experimental means 

 in biology. 



The brown and the white strains of Rattus norvegicus, as well as a 

 few mice and ground squirrels ( Citellus richardsoni) , were employed 

 for the experiments herein reported. 



Two preparations of strychnine, one of free alkaloid and one of 

 sulphate, tested and found to be free from brucin, 5 were used. The 

 free alkaloid was passed through a sieve having 100 meshes to the 

 inch. Two preparations of the adsorption combination of strych- 

 nine sulphate with diatomaceous or infusorial earth, found by the 

 Kjeldahl analysis 6 to contain the amount of the alkaloidal salt 

 stated on the label, were used. Standard 0.1 per cent strychnine sul- 

 phate solution was made up in physiological salt solution on the day 

 of the experiments, lower dilutions being made as required from a 

 freshly prepared 0.1 per cent solution. Thick cornstarch paste was 

 taken to maintain a uniform suspension of the free alkaloid and of 

 the infusorial-earth preparations. These suspensions were prepared 

 in a small mortar, made up to volume in a 100 cc. volumetric flask by 

 the starch paste and water washings from the mortar and thoroughly 

 shaken. Amaranth, which in the concentration employed did not 

 form a visible precipitate with strychnine, was used in some ex- 

 periments for tracing the course of strychnine in the gastro-intestinal 

 tract. 



Injections into the stomach were made with a small hard-rubber 

 urethral catheter, fitted over the outlet of a record syringe. The 

 measurement of the starch-paste suspension therefore was by differ*- 



5 H. E. Buc, formerly of the Bureau of Chemistry, made the tests. 



6 L. J. Jenkins, of the Bureau of Chemistry, made the analysis. 



