PHARMACOLOGICAL ACTION OP TETRA-ALKYL-AMMONIUM COMPOUNDS. 395 



per kg. body-weight cause only a relatively slight fall lasting about two minutes (figs. 

 3 and 4). No evidence of stimulation of the vagal nerve endings in cats or rabbits, 

 such as occurs after the administration of tetra-methyl-ammonium chloride, was 

 obtained. 



The respiration is also much less affected by tetra-ethyl-ammonium chloride than 

 by tetra-methyl-ammonium chloride. After doses of 10 mg. per kg. body- weight 

 intravenously to anaesthetised rabbits, slight diminution in the extent of the respira- 



Fig. 6. — Effect of tetra-ethyl-ammonium chloride on the respiration and blood-pressure of an anaesthetised 

 rabbit. Weight 2500 g. ; ether. Letters as in fig. 3. The effect of stimulating the right phrenic 

 nerve on the respiration is also shown. 



tion and in the irritability of the phrenic nerves may occur, but the latter may be 

 present without any obvious changes in the frequency or depth of the respiration. 

 Doses of 20 mg. per kg. body-weight cause well-marked but transient depression of 

 the respiration, and for about half a minute the phrenic nerves are but slightly 

 irritable (cf. fig. 6). Complete paralysis of the respiration or of the phrenic nerves 

 to intermittent stimulation was not obtained even with this large dose. Tappeiner # 

 also failed to produce with tetra-ethyl-ammonium chloride the temporary paralysis 

 of the respiration which characterises the action of certain closes of tetra-methyl- 

 ammonium chloride. 



The respiration of cats is less susceptible to tetra-ethyl-ammonium chloride 



* hoc. cit 

 TRANS. ROY. SOC. EDIN., VOL. L. PART II. (NO. 12). 55 



