Physiology of the Heart. 139 



Stimulation of these nerves has led to similar results to 

 those furnished by stimulation of the vagus, i. e., retardation 

 of the rate, weakening of the heat and after acceleration. 

 Hence they have been called by me accessory vagi. There 

 seem to be nerves of somewhat similar function in the sea 

 turtle. 



Peculiar Cardiac Inhibition followed by Acceleration. Special 

 attention is called to the following experiment which is be- 

 lieved to be unique in physiology. In a small alligator with 

 the whole brain destroyed for some time, both vagi divided and 

 dead throughout the greater part of their course (stimula- 

 tation not producing cardiac arrest), a sharp tap over the 

 liver and stomach with a dissecting forceps caused car- 

 diac arrest of brief duratio n, then slowed irregular rythm 

 followed by acceleration of a very pronounced kind (from 40 

 to 50 beats). Here then were the usual phenomena of reflex 

 vagus inhibition, as when the vagi and medulla are intact. 

 This experiment was tried three times. It does not seem pos- 

 sible to explain this unparalleled result by present theories. 

 I conclude that the impulses passed through the sympathetic 

 system of nerves and that probably other inhibitory fibres 

 than those of the vagus were concerned, and that accelera- 

 ting fibres were also involved. It is also possible to conceive 

 that terminations of the vagi were in some way reached by 

 these impulses, but in any case the results are new to phy- 

 siology, the only published case at all resembling it being- 

 Marshall Hall's experiment on the eel's stomach (Todd's 

 Cyclopedia of Anat. and Phys., article "Heart.") 



Cardiac Augmentors. As described by Gaskell, there is in 

 the Crocodilia, from the ganglion of the eleventh metamere 

 of the sympathetic chain, a strong well-defined branch 

 passing to the heart. 



Stimulation of this nerve has given rise to [1] accelera- 

 tion following the law of inverse proportion, which seems 

 applicable to all kinds of acceleration. [2] Decided augmen- 

 tation of the force of the beat. This is more marked than 

 the acceleration in rate, and in fact may disguise the effects 

 of the nerve, for no actual acceleration of beat may follow. 



In all cases, stimulation of a genuine cardiac augmentor 



