258 THE HEART, BY F. SCHWEIGGER-SEIDEL. 



mitted that the difference between the vagus and the sympathetic, or, 

 in other words, the difference between the inhibitory and the exciting 

 fibres, is to be sought for in the circumstance that the one acts directly 

 on the muscular substance, the other only indirectly through the in- 

 tervention of the ganglion cells. The latter is supposed to be the 

 mode in which the vagus acts, though no positive proof of the fact 

 has hitherto been adduced. 



Kolliker, indeed, has convinced himself from anatomical investiga- 

 tion that the vagus stands in no direct relation with the ganglion cells, 

 but other observers do not agree with him ; and very recently Bidder,* 

 who has also examined the subject anatomically, has stated that the 

 spiral fibres are fibres of the vagus passing to the ganglion cells, 

 whilst the straight fibres are given off by the cells, and are destined to 

 be peripherically distributed. If, however, Bidder rests his view ex- 

 clusively on the results of sections of the nerves made in frogs, his 

 evidence is diminished in value to some extent, because in these ani- 

 mals the Eami Cardiaci are the only nerves which pass to the heart ; 

 and consequently, when they are divided, not only the inhibitory, but 

 the exciting fibres would undergo degeneration. 



The further distribution of the nerves in the muscular sub- 

 stance of the heart is difficult to follow, as they undergo rapid 

 subdivision, or, at least, but few trunks can be seen. Hence it 

 follows that the fibres are delicate and non-medullated. It is 

 generally acknowledged that ganglia are distributed in the 

 muscular substance. If, however, this be admitted on the au- 

 thority of Kemak,f it is to be remarked that he observed their 

 presence under the microscope only in the case of the calf. 

 I have not been myself successful in discovering such ganglia 

 lying between the fibres in the proper muscular substance, and 

 can only admit that they may be found on a few traversing 

 trunks or branches. 



Friedlander maintains that large numbers of ganglion cells are 

 present in the muscular substance of the heart of the frog, as 

 he believes he has demonstrated the constant existence of such 



* Archiv fur Anatomie u. Physiologie, 1868, p. 1. 

 t Miiller's Archiv, 1844, p. 463. 



J Untersuchungen aus der Physiologische Ldboratorium in Wurzburg, 

 Heft, ii., 1867. 



