DISTRIBUTION OF THE NERVES IN THE SALIVARY GLANDS. 435 



a series of very remarkable peculiarities. In the first place 

 they have such delicate and pliable sheaths, that they some- 

 times appear to be destitute of them. In accordance with this, 

 varicosities form in the coarser trunks, as in the fibres of the 

 brain or spinal cord (see fig. 77), where, however, they become 

 still larger, and form more easily than amongst these. On 

 account of the extraordinary delicacy of the sheath these 

 fibres tear with remarkable facility, and pour forth their 

 contents in the form of myelin drops, which rapidly become 

 stained of a blue-black colour by osinic acid, like these nerves 

 themselves. 



A second peculiarity of the medullated glandular nerves is 

 exhibited in their mode of division, the division occurring so 

 frequently as to have been seen by almost all observers. Accord- 

 ing to my own observation, the number of divisions increases 

 in a most unusual manner towards the periphery, so that 

 almost feathery medullated primitive fibres lie between the 

 alveoli, and give off branches in all directions. 



If we now proceed to the consideration of the terminal organs 

 of the nerve fibres, we must first discuss the relations these bear 

 to the proper tissue of the gland. The salivary tubes, with 

 which we shall best commence our description, are accom- 

 panied by numerous bands of medullated nerve fibres of very 

 various size. Many are in the most intimate relation with 

 the tubes, as is shown in the accompanying figures. In one 

 instance the specimen was fresh (fig. 78), in another it was 

 stained by maceration in perosmic acid (fig. 79). 



These nerves, as seen in figs. 78 and 79, perforate the mem- 

 brana propria, and then break up into a number of fibres, which 

 become finer by further subdivision, and wind around the out- 

 side of the columnar epithelial cells, to form a sub-epithelial 

 plexus, which demands still closer examination. The fibrils 

 lying on the membrana propria are pale and soft, and give the 

 impression of naked axis cylinders. But that they are accom- 

 panied for some distance by the nerve medulla is recognised by 

 the blackening of the osmic acid preparations around the termi- 

 nation of the thicker primitive fibres. The axis cylinders run- 

 ning on the membrana propria branch ultimately into the finest 

 possible varicose fibrils, which have precisely the same characters 



