46 THE HEART 



Since, however, Apathy and Bethe make a similar claim for nerve 

 fibres, their distribution has now an added significance. 



The nerve endings in the heart are both sensory and motor. 

 There is some doubt about the exact distribution of the sensory 

 fibres. It is held by some physiologists that they do not supply 

 the heart at all but only the aorta ; others, however, believe that 

 they end as tree-like expansions very like those in fascia and 

 tendons, in both the epicardium and endocardium. According to 

 Smirnow, all the sensory fibres run in the depressor branch of 

 the vagus, since after section of this nerve in the cat no sensory 

 nerve endings can be detected. 



The motor nerve endings come from both the vagus and the 

 sympathetic nerves. Gerlach states that the motor nerves accom- 

 pany the fibrous tissue among the heart muscle and finally end 

 as a delicate peri-muscular layer embracing the muscle fibres. 

 Heymann and Demoor claim that every heart fibre is surrounded 

 by a nervous network right down to the apex of the heart. 



In regard to the ganglion cells of the heart, Dogiel has divided 

 them into three types. The differences between the types are 

 mainly in the shape and size of the nucleus, the length of axon 

 and the number and form of the dendrites. The distribution of 

 the ganglion cells is a matter of prime importance. It is certain 

 that the auricular part of the heart is rich in these cells, which 

 are often arranged in groups corresponding to Remak's, Ludwig's, 

 and Bidder's ganglia in the frog's heart. These are respectively 

 situated at the sino-auricular junction, on the interauricular septum 

 and round the A-V groove. The distribution of ganglion cells in 

 the ventricle is a vexed point. Dogiel and his pupils find that 

 they undoubtedly occur in the upper third of this chamber. 

 The lower two-thirds is, usually speaking, ganglion-free. This is 

 true for the hearts of such animals as the sheep, calf, dog, sucking 

 pig, duck, turkey, and chicken (Kasem-Beck). Ganglion cells have 

 also been found in the ventricle of the rabbit and ape ( Vignal), and 

 of the mouse (Berkley), and in the ventricle and bulbus of the 

 frog (Dogiel). 



Yet against this view such authorities as Engelmann, His, 

 Krehl and Romberg state that the ventricle contains no ganglion 

 cells either in warm-blooded or cold-blooded animals. In many 

 cases it appears to turn upon the interpretation placed upon 

 certain histological appearances. For instance, Engelmann claims 



