TOXICITY OF STRYCHNINE TO THE RAT. 



occurred. The size of the dose of strychnine required to produce 

 death tends to decrease as the evolutionary scale is ascended. Un- 

 explainable differences, however, are reported between the more 

 closely related species such as rats and mice (Table 1). On the 

 other hand, a low resistance to strychnine is found (25) in animals 

 having a higher morphological type of pyramidal tract in the spinal 

 cords (rabbits, cats, and dogs). 



Table 1. — Specie* tolerance to strychnine salts (minimum lethal <m<i sublethal 



subcutaneous dose) . 



Animal. 



Usual sub- 

 lethal dose, 

 per kilo. 



Usual 



lethal dose, 



per kilo. 



Citation. 



Rat 



Milligrams. 



2.5 



2.0 



.8 



.76 



Milligrams. 

 3.0 to 3. 5 

 3.0 

 1.2 

 .77 

 1.5 

 3.41 

 3.0 to 3. 5 

 4.4 

 .5 

 0. 55 to 0. 60 

 .57 

 .40 

 0. 32 to 0. 384 

 0. 35 to 0. 42 



Table 4. 



Do 



Hunt (12).i 





Do. 



Do 



Falck (6). 2 



Do 



Page 14. 





3.4 

 2.5 



Falck (6). 2 



Do 



Hale (9). 



Do 



Hatcher and Eggleston (11). 



Rabbit 



0.4 

 0. 45 to 0. 50 



Hare (10). 



Do 



Meltzer and Salant (16). 



Do 



Falck (5). 2 



Cat 



0.35 



Cutler and Alton (4). 



Do 



Hatcher and Eggleston (ll). 3 



Dog 





Do. 



Do 



0.30 

 0. 6 to 0. 7 



Hale (3). 



Ground squirrel 



0.7 upward. 



Table 8. 







i Personal communication from Dr. Reid Hunt. 



2 The salt administered by Falck was the nitrate. All other observers used sulphate. 



3 Hatcher and Eggleston (11) gave their dosages in terms of the alkaloid, but actually the sulphate was 

 administered. The data given here have therefore been recalculated. The smaller dosages of these authors 

 are for a solution containing 0.1 per cent of the alkaloid, the higher dose for 0.01 per cent solution. 



The results from the type of experimentation shown in Table 1 

 are subject to fewer disturbing factors, so far as strychnine is con- 

 cerned, than those from either the intravenous or gastro-intestinal 

 methods of administration (11). These data, therefore, may be 

 taken as representing the true species tolerance. 



That the temperature of the environment also is an important 

 factor is shown by the results of experiments on cold-blooded ani- 

 mals, in which it is easily possible to obtain a range of temperature 

 amounting to 25° C. (29). Spasms occur more readily in frogs kept 

 at 5° and at 30° C. than in those kept at 15° C. (7). The type of 

 spasm also varies with the temperature. While frogs held at low 

 temperatures have periods of long-continued tonic spasms, lasting 

 sometimes for days, and separated by intervals of incomplete relaxa- 

 tion, those held at 30° C. undergo short spasms with more complete 

 intervening relaxation. The short spasm, with practically complete 

 relaxation, therefore, is the type observed in the homothermal, or so- 

 called " warm-blooded " animals, which have a temperature-maintain- 

 ing mechanism. Hibernation may directly affect the toxicity of and 

 the behavior toward the drug, thus offering a possible explanation 



