PHARMACOLOGICAL ACTION OF TETRA-ALKYL-AMMONIUM COMPOUNDS. 489 



certain unusual effects obtained in anaesthetised animals with tetra-methyl-ammonium 

 chloride. On a few occasions out of more than a hundred injections of this substance 

 a very marked immediate rise has occurred. The greatest of these is shown in 

 fig. 3. It was obtained in an anaesthetised rabbit after intravenous injections of 

 25 mg. and 50 mg. of tetra-ethyl-ammonium chloride and 30 mg. and 50 mg. of 

 methyl-tri-ethyl-ammonium chloride had been successively given, and all of which 

 caused a fall of blood-pressure. The form of the tracing strongly suggests a vascular 



PiWiiMOTW^^ 



Fig. 3. — Unusual rise of blood-pressure produced by 2 mg. tetra-methyl-ammonium chloride in 

 anaesthetised rabbit after previous injections of large doses of tetra-ethyl- and methyl-tri- 

 ethyl-ammonium chlorides. Letters as in fig. 1 . 



effect of peripheral origin ; but, owing to the rarity with which it has occurred and 

 the difficulty of determining the conditions which induce it, it has not been possible 

 to determine the point. 



The temporary increase in respiratory activity prior to the depression has been 

 most evident after injections of tri-methyl-ethyl-ammonium chloride (fig. 4). A 

 slighter stimulant effect has occurred after the administration of di-methyl-di-ethyl- 

 ammonium chloride (fig. 2), and on one occasion a still slighter apparent stimulation 

 occurred after an injection of methyl-tri-ethyl-ammonium chloride. A brief stimula- 

 tion of the respiration may also follow the injection of tetra-methyl-ammonium 



TRANS. ROY. SOC. EDIN., VOL. L. PART II. (NO. 17). 70 



