37 



and passing from them of ultimately the same size, though occa- 

 sionally there is a slight alteration in calibre. Much more rarely than 

 the smooth exterior, an apparent short ramus arises from one side of 

 the bulb, but it is here necessary to make allowance for a possible 

 deception in these cases, in so far that a branch of some varicose 

 fibre passing under the ganglionic body might reappear as if it arose 

 directly from the ganglionic swelling itself, though this is of course by 

 no means certain. 



It is impossible in these structures, which are always most deeply 

 stained, to discover anything of a cellular structure, yet as they are 

 very many times larger than any of the varicose swellings that are 

 met with upon the fibres of the first order, we think that after all 

 allowance has been made for possible visual errors, that they must be 

 considered bi-polar cells situated in the paths of the nerve fibres, and 

 that the end-apparatus should be looked upon as their terminal ex- 

 pansion. 



A most complicated question now arises: should these endings be 

 considered motor or sensory? The type of end expansion, especially 

 those of figs. 3 and 4 approach in many ways well known types of 

 motor endings 1 ), but the swelling in the pathway of the nerve, which 

 is far too large to be thought of as a nucleus of the myeline sheath 

 of the nerve, supposing such sheath to occur in this situation, is 

 unknown with any hitherto discovered motor ending, but on the con- 

 trary from the recent researches of Lenhossek 2 ) and Retzius 3 ) is of 

 common occurrence in the paths of sensory nerves. Are we then to 

 consider these end-expansions as sensory or even reflex-sensory, and 

 do they belong to the fibres of the sympathetic system or to the ter- 

 minal endings of a nerve whose function is to conduct cerebral wards ? 

 Further research only can answer these questions, and the sensory 

 hypothesis is advanced as the most plausible one offering, and if the 

 endings are found to be constant they will add a further advance to 

 our knowledge of the nervous systems of mammalia. 



Another histological element that has apparently escaped previous 

 notice, but of vast importance in the consideration of the physiological 

 action of the ventricle muscle now claims our attention, namely the 



1) See Tafel XVII, Nervenendigungen von Eana, Fig. 8, of Retzius, 

 Biol, Unteruch., N. F. Ill, 1892, also Babes,' Atlas der path. Hist. d. 

 Nervensyst., 1. Lieferung, Plate 1. 



2) Arch. f. mikr. Anatomie, Bd. 39, 1892. 



3) Biol. Unters., N. F. IY, 1892, p. 51. 



