124 DR. KLEIX. 



one hour ; after that time the tongue is rinsed in distilled 

 Avater, taken off from the cork and exposed in distillrd water 

 to the light until it becomes dark. The tongue is then placed 

 in common alcohol for twenty-four or forty-eight hours, a 

 sufficient time to harden it so far as to be able to make hori- 

 zontal sections. The sections after they have been washed 

 in Avater are mounted in glycerine. The preparations which 

 I am going to describe belong to the deeper muscular por- 

 tions of the tongue. The muscular fibres appear here grayish 

 violet, the connective-tissue-corpuscles, Avell known by their 

 bizarre shape, are, except the nucleus, dark coloured, the 

 non-medullated nerve-fibres appear dark violet, and the 

 blood-vessels more or less a grayish violet colour. In the inter- 

 muscular connective-tissue, which contains a great number of 

 connective-tissue-corpuscles, w^e find some isolated medullated 

 nerve-fibres j)rovided with a thick nucleated sheath of Schw^ann. 

 From these spring off' more or less numerous non-medullated 

 nerve-fibres which are also provided with nuclei. These 

 nerve-fibres join so as to make a not very dense plexus. If 

 Ave follow a very small artery (fig. 1), Ave find a broad non- 

 mcduUated nucleated nerve-fibre approaching the vessel and 

 accompanying it either Avithout branching, or else dividing 

 into tAVO nucleated branches which are still to be regarded 

 as coarse nerve-fibres. 



The tAvo branches accomi^any the artery for a shorter or 

 longer distance on opposite sides, and bend round the vessel 

 once or tAvice. Or we see a coarse non-medullated nucleated 

 ner^^e-fibre crossing the artery, and Avhile doing so giving 

 off" two branches which bear the same relation to the vessel 

 as above. 



Besides these coarser nerve- fibres Avliich accompany the 

 artery we find a great number of finer fibres vA'hich accompany 

 the vessel. They bend round the vessel several times, and join 

 by lateral branches together, forming a plexus which surrovnids 

 the artery like a sheath. There cannot be any doubt that 

 the fibres just mentioned are nerve-fibres. First of all they 

 can be traced Avith the greatest certainty to the above-men- 

 tioned coarser nucleated non-medullated nerve-fibres ; and 

 secondly, many of them exhibit in their course here and 

 there a nucleated SAvelling. 



To recapitulate, we see that from the coarser nucleated 

 non-medullated nerA'e-fibres AAliich accompany an artery, there 

 spring off" a number of finer nerA'e-fibres still proA'ided Avith 

 rare nuclei, Avhich finer fibres form a rather dense plexus 

 like a perivascular sheath. Where this perivascular nervous 

 sheath is very richly developed, and the wall of the artery 



