614: EXPERIMENTAL INVESTIGATION OF THE ACTION OF MEDICINES. 



effects of the poisons on which they depend, and not merely 

 endeavour to quicken their elimination. 



Action of Various Drugs on the Inhibitory A2)paratus. — From 

 experiments which he has made on the excised hearts of frogs 

 with Ludwig and Coats' apparatus, Boehm has come to the 

 conclusion that conia paralyses the terminal filaments of the 

 vagus ; nicotia the intermediate structure between them and the 

 inhibitory ganglia ; and that others, such as atropia, hyoscyamia, 

 daturia, physostigma, aconitia, delphinia and veratria, diminish 

 or destroy the irritability of the inhibitory ganglia themselves. 

 It is rather extraordinary to find physostigma in this list ; and 

 it would thus seem that the pure alkaloid which Boehm used 

 had a different action from the tincture used by Yon Bezold, 

 unless it be that the result depends simply on a difference in 

 the amount of the poison used. 



Accelerating Ganglia in the Heart. — We infer the presence of 

 quickening ganglia in the heart from the effects produced by 

 irritating the vagus after its inhibitory power has been destroyed 

 by the administration of nicotia or atropia. When irritation is 

 then applied to the nerve, it no longer produces retardation, 

 but, on the contrary, a decided acceleration of the cardiac pulsa- 

 tions. This shows that the vagus contains fibres which quicken 

 the heart, and that these are unaffected by the drugs which 

 have paralysed the others. The quickening, however, does not 

 take place till some time after the application of the irritant, 

 and, if it be applied only for a short time, no acceleration may 

 take place till after its removal ; but, after it does occur, it 

 remains for a considerable time. If we irritate the heart 

 directly, instead of irritating the nerve, its beats are quickened 

 at once, and the acceleration does not last long after the irrita- 

 tion is discontinued. This shows that, when we stimulate the 

 quickening nerves, we do not act directly on the motor ganglia M 

 (Fig. 138), as we do when we irritate the heart itself, or as we 

 should do if the quickening fibres ended directly in them ; 

 and we therefore infer the existence of the accelerating ganglia 

 Q between the quickening nerves s and the motor ganglia M. 

 The accelerating apparatus seems to be stimulated by veratria, 

 for we find that the cardiac pulsations are increased by its 



