clxvi Journal of Comparative Neurology. 



not differ in any material way from those of other organs. Lastly, 

 that neural enlargements, that have never been found among the 

 doubtful fibres, do occur, though the silver stain does not show them 

 with frequency. Medullated fibres have a very doubtful existence 

 within the proper limits of the hepatic organ, the osmium-copper- 

 hematoxylin stain having failed completely to bring them into view, 

 while the silver method gives no indication that they are present. 



III. With this study on The Intrinsic Pulmonary Nerves in 

 Mammalia our readers are already familiar (Vol. Ill, pp. 107-111). 



IV. The Intrinsic Nerve Supply of the Cardiac Ventricles in 

 Certain Vertebrates. 



1. The interspaces of the muscular bundles of the heart of 

 mammalians, batrachians, Amiurus, chelonians, and aves, are thickly 

 filled, from the apex of the ventricles to the auriculo-ventricular 

 groove, by a dense network of coarser and finer anastomosing nerve 

 fibres, which touch at some point each bundle, but end-terminations 

 are not always to be found in contact with every muscular cell. 



2. The terminal apparatus of the varicose networks acting upon 

 the muscular fibres, is most frequently at the end of a short trans- 

 verse ramus, arising in the course of a longitudinal fibre, and has al- 

 ways the aspect of a simple bulb of varying size. 



3. Neural enlargements of considerable diameter are found de- 

 veloped in all the species of animals examined, upon the fibres of the 

 inter-muscular network. These neural swellings are probably nucle- 

 ated. Transition forms from the smallest varicosity on the thinnest 

 nerve fibre, to enlargements .01 mm. or longer, may be found in all 

 well stained sections. 



4. Nerve cells of the sympathetic system have a probable exist- 

 ence within the ventricular walls, and are in form spindle, pyramidal, 

 or stomach-shaped. The axis-cylinders from these cells (mouse), are 

 directly connected with the fibres of the varicose plexuses. A spray 

 of terminal fibres upon the isolated cells is probable. 



5. More complex end-apparatus than the simple bulb of the 

 varicose networks has only been seen within the ventricles of the high- 

 est orders of vertebrates examined, the dog, mouse, and albino rat, 

 but from the rarity of the observations their constant presence is by 

 no means positive, but it is probable. True end-plates have not been 

 found. 



6- All the eight species of animals examined presented similar 

 intrinsic ventricular, nervous structures, muscular networks with sim- 

 ple bulbar end-apparatus, neural thickenings, and cell-like bodies re- 



