198 THE TISSUE OF THE ORGANIC MUSCLES, BY J. ARNOLD. 



the muscular fibre from different sides ; but, whatever may be 

 their number, they all pass towards the granules of the nucleus, 

 which might therefore be regarded as the extremities of the 

 fibres, were it not that in many cases they again give off fila- 

 ments, which, traversing the substance of the nucleus and of 

 the muscular fibre in the opposite direction, enter the intra-mus- 

 cular plexus. Consequently these granules are not the free 

 ends of the smallest nerve fibres, but only the nodal points of 

 the finest nerve plexus lying within the nucleus. The best 

 demonstration of these relations also is to be obtained from 

 transverse sections (fig. 33, c). 



After Klebs* had in the first instance recognised that an intimate 

 relation existed between the finest nerve filaments and the substance 

 of the muscular fibres, it was shown by Frankenhauserf that the 

 former penetrated into the interior of the latter, and proceeded to the 

 granules of the nucleus, to which he applied the name of nuclear cor- 

 puscles (Nucleoli, Kernkorperchen). The statements above made are 

 the result of careful investigations which I have elsewhere more fully 

 reported. As regards the relations of the finest nerve filaments to the 

 substance of the muscular fibre and its nucleus, as well as to the 

 intra-nuclear granules, I coincide with Frankenhauser. On the other 

 hand, I was unable to recognise the actual extremities of the nerve 

 fibres in the granules of the nucleus ; they rather appear to me as 

 nodal points of the finest nerve plexus lying in the interior of the 

 nucleus. 



DISTRIBUTION. Smooth muscular fibres are widely distri- 

 buted through the body. In the organs of respiration they 

 are seen to form layers of circular fibres in the posterior wall of 

 the trachea, and in the bronchi. Their presence in the walls of 

 the alveoli of the lungs in man and mammals is still doubtful, 

 being admitted by some observers, whilst it is denied by others. 

 Muscular fibres are, however, certainly present in the alveoli 

 of the lungs in infants, and in the lungsacs of the frog, sala- 

 mander, and triton. 



* Loc. cit. 



f Die Nen-en der Gebdrmutter und ihre Endigungen in den Glatten 

 Muskelfasern, " The Nerves of the Uterus, and their Mode of Termination 

 in smooth Muscular Fibres," 1867. 



