31' DISTRIBUTION OF NON-MEDULLATED NERVE-FIBRES. 



In the septum of the cisterna lyinphatica we find the 

 same relations which have just heen descrihed, repeated. 

 Cyon (37) describes non-medullated fibres from this septum 

 which are distinguished by the oblong nuclei intercalated in 

 their course, and have a striated appearance ; these he repre- 

 sents as running free in the tissues. With respect to the 

 latter point, I cannot agree with Cyon, since I am able to 

 trace in my gold preparations far finer nerve-fibres than 

 Cyon has seen ; and these, as I have stated, are united into a 

 network. 



We find in the larger and middle-sized arteries and veins, 

 nerves of the second order which run in the adventitia and 

 there give off numerous fine fibres; these are united into a 

 network situated in the innermost parts of the adventitia ; 

 they have, generally speaking, in the arteries, a less distinctly 

 sinuous course than in the veins. In illustration of this point, 

 I would refer to those represented in PI. IV, figs. 12 a and 

 12 B. With respect to the nerves of the inner vascular walls 

 I cannot make any assertion worth recording. 



In the smaller veins and capillaries we find just the same 

 relations as in those of the nictitating membrane. We 

 will just mention, although it is repeating what has been 

 already said, that here also non-meduilated fibres of the 

 second order, provided with a nucleated slieath, surround the 

 vessels in a complicated manner and give off branches — 

 nerves of the third order — which are united into a plexus 

 forming a sheath around the vessel ; finally, there arise from 

 these exceedingly fine nervous threads, nerves of the fourth 

 order, which form a network in the vascular wall itself. No 

 connection between a thread of this kind and a nucleus of 

 the vascular wall is demonstrable. 



Before closing these remarks, we wish to say a few words 

 respecting the pigment-cells which occur in the mesentery 

 and in the septum of the cisterna lymphatica. It is by no means 

 our object to describe the anatomical relations of the pigment- 

 cells in the fresh state and in gold preparations ; since we 

 should have nothing to add to what has been already brought 

 forward with respect to the nictitating membrane, and might, 

 therefore, be afraid of too severely taxing the patience of 

 our readers. I may, however, just be allowed to state that 

 in the pigment-cells of the large arteries of the fresh me- 

 sentery, cells Avhich resemble black spherical lumps, I have 

 repeatedly, by the addition of a few drops of a one-per-cent. 

 solution of acetic acid, convinced myself of the presence of 

 numerous ramified unpigniented processes. 



In the subjoined plates, Plate I, fig. 1, contains the repre- 



