J.IODE OF ACTION OF STrtYCIINIXE. S-jO 



division of the spinal cord at the occiput. It has been found by 

 Prokop Rokitansky that the movements do not cease completely 

 after division of the cord, Avhen the animal has been previously 

 poisoned by strychnia, and that both vaso-motor reflex and respi- 

 ratory movements can be reinduced in such animals by strychnia 

 administered after the cord has been divided, cf. antea^ p. 323. 

 It occurred to us that possibly a similar phenomenon might be 

 observed in the heart. We therefore administered strychnia to 

 a frog, and as soon as the spasm occurred, the animal was 

 killed and a ligature placed round the heart. No cessation of 

 movement, however, was observed. When a frog was first 

 killed, however, and still-stand of the heart was induced by 

 application of a ligature, a solution of strychnia placed on thQ 

 outside of the heart did not reinduce rhythmical pulsations, but 

 when the solution was injected by a line pipette into the inte- 

 rior of the ventricle, rhythmical pulsations again commenced. 

 This rhythm, however, was independent of that which the 

 venous sinus still continued to pursue. After maintaining this 

 for some minutes, it again stopped, and the auricle was seen to 

 contract after the ventricle. The aorta was now cut, and the 

 ventricle again contracted, but the auricles remained quiescent. 

 On stimulating the ventricle, it now went on beating regularly. 

 From these experiments it would appear that the still-stand 

 induced by ligature of the venous sinus has a deficiency of 

 motor power in the auricle and ventricle, and that when we 

 increase the excitability of the ganglia in these parts by warmth 

 or by strychnia, the pulsations recommence. The following 

 seems to us the best explanation of the phenomena observed. 

 The motor ganglia of the heart, we think, are in all probability- 

 called into action by reflex stimulation. This reflex stimulation 

 may originate in impressions conveyed to them by afferent 

 nerves from the internal or external surface of the heart, or by 

 impressions conveyed to them by the afferent nerves from the 

 other cavities of the heart. We think, also, that although they 

 respond to the stimuli conveyed reflexly from the internal or 

 external surfaces of that part of the heart in which they are 

 contained — as shown, for example, in contraction of the ven- 

 tricle on stimulation by a needle or an electrical current — they 



