482 PROFESSOR C. R. MARSHALL ON THE 



the solutions possessing the same conductivity as 0'895 per cent, sodium chloride ; 

 and in a parallel column the strengths calculated on the assumption that the 

 compounds are ionised to the same extent as sodium chloride. 



It will be seen that there is a diminution in the degree of ionisation as we pass 

 from tetra-methyl-ammonium chloride to tetra-ethyl-ammonium chloride. Bredig * 

 found that tetra-ethyl-ammonium hydroxide was ionised to a smaller extent than 

 tetra-methyl-ammonium hydroxide. 



General Action. 



The relative toxic effects of these substances have been investigated on frogs by 

 injecting isotonic solutions or these diluted with Ringer's solution into the dorsal 

 lymph-sac, and by observing the effect on tadpoles of known concentrations of the 

 different substances. The effects produced were, relative to the actions of tetra- 

 methyl-ammonium chloride and tetra-ethyl-ammonium chloride, broadly those which 

 might have been expected from the chemical composition of the respective sub- 

 stances. Tri-methyl-ethyl-ammonium chloride in effective doses produced paralysis, 

 and rarely a few early muscular twitches ; di-methyl-di-ethyl-ammonium chloride 

 caused chiefly paralysis, with somewhat more distinct evidence of increased 

 irritability of the motor nerve endings ; methyl-tri-ethyl-ammonium chloride caused 

 slight irregular muscular movements and tremors, followed, when sufficient doses 

 were given, by paralysis. The following brief protocols of a series of experiments, 

 made on the same day on winter frogs of the same batch kept under the same 

 conditions, indicates the relative intensities of their actions. The frogs weighed 

 31 to 34 grammes each, and the dose injected into the dorsal lymph-sac was 0'5 c.c. 

 of an equi-conductivity solution in each case. 



Tri-methyl-ethyl-ammonium Chloride. — 0*18 mg. per gramme of frog. Two and a 

 half minutes, submandibular movements ceased. Eight minutes, twitch of thigh 

 muscles. Fifteen minutes, paralysed. No recovery occurred. 



Di-methyl-di-ethyl-ammonium Chloride. — 0"22 mg. per gramme of frog. Six and a 

 half minutes, submandibular movements ceased. Eighteen minutes, recovered from 

 back position after several attempts. Thirty minutes, did not recover from back position 

 although many efforts made. Sixty minutes, still laid on back ; moves when probed 

 with pencil ; respiration somewhat more distinct. Eighty minutes, made few 

 spontaneous movements of a tremulous character. Twenty hours, has turned over 

 during night ; bears back position ; made few attempts, marked by irregular 

 muscular movements, to recover. Third day, still on back ; irregular muscular 

 contractions produced by stimulating with pencil. Died on following day. 



Methyl-tri-ethyl-ammonium Chloride. — 0*25 mg. per gramme of frog. Forty-five 

 minutes, no noticeable symptoms. Fifty minutes, recovered from back position 

 once but not twice ; movements exhibited tremors ; recovered from back four 



* Zeitschr. f. physik. Chem., xiii. p. 299 [1894]. 



