26 DR. KLEIN. 



a capillary vessel or a small vein, and when they have come 

 quite close up to it, we see them divide into two branches. At 

 the point of division we notice an oblong nucleus. Now, one 

 of the two branches remains on the same side of the vessel, 

 and accompanies it for some distance, while the other passes 

 across the vessel, either obliquely or at a right angle ; arrived 

 at the other side, it bends away and travels now in the same 

 direction as its partner, close to the vessel, or else it leaves the 

 vessel after first sending off a fine branch which accompa- 

 nies the same. 



The fibres twine around the vessel in many cases once or 

 more ; they give ofi',in every case, finer twigs which correspond 

 to the above-mentioned nerves of the third order. By the union 

 of these there is formed a rich plexus, which surrounds the 

 vessel just like a kind of nervous sheath. Finally there pro- 

 ceed from these very fine threads, which correspond to the 

 nerves of the fourth order, and here possess granular swell- 

 ings. Tbey lie for the most part in the vascular wall, divide 

 dichotomously, and are finally united to form a network. 

 On surface views there is certainly no small difiiculty in de- 

 ciding whether such a structure as a fine nervous thread, 

 which can just be followed by No. 8 Hartnack, courses in or 

 on the wall of the capillary ; but in the case of which an 

 illustration is given in fig. 5, I believe I can speak with cer- 

 tainty; a represents a capillary filled with blood-corpuscles. 

 I can now, with the No. 10 immersion, follow the one or 

 the other thread quite distinctly to the plane, immediately 

 under which, by the very slightest turn of the micrometer 

 screw, the most superficial blood-corpuscles come into view; 

 this layer I find again leaving and running towards the other 

 side. Thus I am justified in assuming that threads do 

 course within the wall of the vessel. I must once more 

 insist upon it as a fact that these threads have nothing to 

 do with the intercellular cement-lines of the endothelium, 

 of the capillary, but are nerve-threads ; on account both 

 of their course and of their characteristic appearance, 

 they can be considered as nothing else ; for this fur- 

 ther reason, too, above all, that I am able to follow them 

 from unmistakable nerve-fibres with any amount of cer- 

 tainty that can be desired. I was never able to find 

 such a thread connected with the nucleus of the vascular 

 wall, and that after careful investigation, although I con- 

 sidered such to be the case on superficial observation. What 

 the authors named above describe as the finest nerves on the 

 capillaries are not by a great deal the finest nerves. 



To recapitulate, in a few words, the relation of the nerves to 



