396 PHARMACOLOGICAL ACTION OF TETRA-ALKYL- AMMONIUM COMPOUNDS. 



than that of rabbits ; intravenous injections of 20 to 25 mg. per kg. body-weight 

 causing only slight diminution of depth, sometimes accompanied by slight slowing of 

 the respiration (cf. figs. 3 and 4). 



In decerebrate animals the effects produced on the respiration are similar to 

 those seen in anaesthetised animals. There is no diminished susceptibility to the de- 

 pressant action of this substance in decerebrate as compared with anaesthetised animals, 

 such as occurs in the case of tetra-methyl-ammonium chloride. On the contrary, the 

 respiration of decerebrate animals seemed to be somewhat more sensitive than that 

 of anaesthetised animals. The intravenous injection of 27 mg. per kg. into a decere- 

 brate rabbit caused permanent paralysis of the respiration, an effect not obtained in 

 anaesthetised non-decerebrate animals, and in one experiment on a decerebrate cat in 

 which the respiration, although deep, was slow (nine per minute) the intravenous 

 injection of 10 mg. per kg. body- weight caused cessation of the respiration for thirty- 

 five seconds. Afterwards the respiration became somewhat deeper and quicker. A 

 previous injection of 5 mg. per kg. to this animal caused merely slight and temporary 

 diminution in the depth of the respiration, so that the slightly increased activity seen 

 after the larger dose was a secondary effect. During the respiratory depression 

 induced by large doses of tetra-ethyl-ammonium chloride in rabbits a temporary 

 increase in respiratory activity, which is also a secondary action, occurs in both 

 anaesthetised and decerebrate animals (figs. 5 and 6). No evidence of stimulation of 

 the respiratory centre in decerebrate animals, such as occurs after the injection of 

 tetra-methyl-ammonium chloride, was obtained with any dose of tetra-ethyl-ammonium 

 chloride. 



