MIXUTE ANATOMY OF THE HEART. 259 



cells in still pulsating portions of muscle, in which there were not, in 

 some instances, more than two or three muscular fibres. His state- 

 ments, however, are not sufficiently precise. He has given no de- 

 scription of either the size, form, or appearance of the supposed 

 ganglion cells, and has made no investigations to show their connec- 

 tion with nerve fibres. 



We possess a few observations respecting the mode of ter- 

 mination of the nerves in the muscular tissue of the heart, 

 that have been made by Kolliker and Krause. Kolliker 

 considers that in the frog the pale nucleated fibres running 

 on and in the secondary muscular bundles, terminate in the 

 same mode as the nerves of the voluntary muscles ; whilst 

 Krause states that " the double-contoured nerve fibres of the 

 cardiac muscle end in motor terminal plates ; and hence the 

 peculiar operation of the cardiac nerves receives no explanation 

 from the mode in which they terminate."* 



That the relations of the cardiac nerves must differ from 

 those distributed to the muscles of the trunk is probable on 

 a priori grounds, from the different arrangement of the mus- 

 cular elements ; for, as the several muscle cells preserve their 

 independence, it is easy to conceive that their mode of inner- 

 vation would be peculiar, and would present an analogy to 

 that of the smooth muscular tissue. Further inquiry is 

 requisite to determine the precise mode in which the ultimate 

 distribution of the nerves is effected, but the following re- 

 marks may be provisionally made for the purposes of com- 

 parison with the arrangements presented by other muscles. 



The nerves run in the connective tissue accompanying the 

 capillaries and occupying the fissures between the muscle cells, 

 and appear in the form of delicate nucleated fibres, resembling 

 those which are elsewhere seen to constitute the peripheric 

 terminations. It is difficult, even in very thin layers 

 of muscle, to discover the extremely delicate fibres. The 

 nuclei of the capillaries, of the nerves, and of the muscle, 

 however different their characters may be, confuse the 

 microscopic image to "so great an extent that no other course 



* Anatomic des Kaninchens. Leipzig, 1868, p. 178. 



