GANGLION CELLS IN THE HEART. 



197 



is seen in the isolated heart out of the body, and necessitates a clamp in the 

 auriculo-ventricular groove for its production. I have never seen anything of 

 the sort in the auricle of the land-tortoise. 



Since the publication of Fano's paper, Botazzi 1 has observed a somewhat 

 similar phenomenon in the auricles of Rana esculenta and Bufo viridis. He 

 has failed to see it in Testudo grmca, Tropidonotus natrix, Lacerta viridis, 

 Anguitta vulgaris, Rana temporaria. In Bufo vulgaris he has observed some- 

 thing of the same kind. 



The curves which Fano obtained from the auricle of Emys resemble closely 

 the curves obtained by v. Frey, 2 when a muscle is stimulated with rhythmical 

 isochronic stimuli, and at the same time supported to different extents. In 

 consequence of this resemblance, Fano was led to the conclusion that the 

 rhythmical tonic contractions were due to slow rhythmical contractions of some 

 contractile substance, different to that to which the normal or fundamental 

 contractions were due. This different contractile substance may be a different 

 kind of muscular tissue, more nearly approaching unstriped, interspersed among 

 the auricular fibres proper, or, according to Botazzi, the phenomenon may be 

 due to the contraction of the sarcoplasm as distinct from that of the aniso- 

 tropic substance of the muscle. This latter explanation seems to me difficult 

 to accept, considering that the phenomenon is confined to the auricles of the 

 hearts of only a few cold-blooded animals ; the other explanation seems more 

 possible ; it requires, however, careful histological examination of the auricles of 

 Emys, such as has not yet been done. 



THE MEANING OF THE GANGLION CELLS IN THE HEART, AND 

 THEIR EELATION TO THE CARDIAC NERVES. 



So far, I have explained all the phenomena, both of the beat of the 

 heart and the sequence of its contractions, etc., without bringing in 

 ganglion cells at all, and the upholders of special nerve centres in the 

 heart have a perfect right to ask, What then are the ganglion cells 

 in the heart ? What function do yon attribute to them ? That is a 

 question which I am ready to answer, and to answer with confidence, 

 as follows : The ganglion cells in the heart are part of the great 

 group of ganglion cells which are situated on the course of the small- 

 fibred efferent nerves supplying the viscera. These cells form the 

 outlying vagrant groups of nerve cells which are known by the name 

 of the sympathetic and cerebro-spinal ganglia. In the case of the 

 heart, the ganglion cells are the cells belonging to the small-fibred 

 efferent cardiac fibres of the vagus, just as some of the cells 

 in the ganglion stellatum and in the inferior cervical ganglion are 

 the cells belonging to the small-fibred efferent cardiac fibres of the 

 augmentor nerve. There is no more reason to assign special functions 

 to these cells than to any of the other peripheral efferent nerve cells. 

 They are cells connected only with the inhibitory fibres of the vagus, 

 and as such are simply part and parcel of the mechanism of inhibition, 

 just as the corresponding cells in the ganglion stellatum are simply part 

 and parcel of the augmentor mechanism. 



The evidence upon which these statements is based will be best 

 appreciated, if I relate the history of our present knowledge of the 

 relations between the cardiac nerves and these peripheral ganglion 

 cells. 



1 Journ. PhysioL, Cambridge and London, 1897, vol. xxi. p. 1. 



2 Beitr. z. Physiol. C. Ludwig z. s. 70 Geburtst. gew., Leipzig, 1887, S. 55. 



