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cylinderfortsatz der Wirbelthiere, ein direkter Uebergang, oder, wie 
bei dem Markfortsatz der Acephalen, ein indirekter Uebergang zur 
Peripherie durch Vermittlung eines interponierten Netzes stattfindet. « 
He believes, thus, the unipolar, »geminipolen« and »pseudobipolaren« 
cells to be the only ones from which »eine nervose Erregung aus- 
gehen, resp. in denen sie allein perzipiert werden kann«, whilst the 
multipolar cells are »Sammelorte fur diese Reize« and the »oppositi- 
polen« cells must be considered as »Faseranschwellungen« (vide 1. c. 
p. 422). 
Regarding the structure of the >^dotted substance«, he arrives at 
the result, after having mentioned some previous writers: »dass niir 
Haller die Struktur der Marksubstanz erkannt hat, DiETL dieselbe 
zu ahnen schien, wahrend alle iibrigen Autoren sich mit Bemerkun- 
gen wie »Filz feinster Fasern«, >^Gewirr feiner Fåserchen« etc. ab- 
finden.« If Rawitz had known works such as, forinstance, that of 
Hermann, which he does not seem to know, he would certainly 
have aknowledged that, also, other writers have tried, and not quite 
without success, to penetrate into this difficult subject. Rawitz's 
observations are even in some respects very like those of Hermann. 
Rav^iTZ adopts Dietls designation » Marksubstanz «, as it is, in 
his opinion, more characteristic than »Punktsubstanz«, which he even 
declares to be incorrect; the reason why he does not, however, 
say. Upon the whole, I think it a very doubtful thing to give 
new designations where an old and well known one is present 
and generally used, which is the case here. I think it the more 
so when the new designation can scarcely be said to be a more 
characteristic one as to the structure; that it is so as to the contents 
does not even seem to me to be quite evident. » Marksubstanz « is 
not used for the same reason that Dietl uses it, viz. because it is 
situated in the »Mark« or centre of the ganglia, but because it, 
according to Rawitz, contains »eine nervenmarkahnliche Substanz, 
welche unter gevisse Bedingungen die characteristischen Erscheinun- 
gen des Myelin darbietet.« That it really is »Mark« or myeline 
Rawitz has observed, I do not think is at all proved in his descrip- 
tion; why may it not be a substance similar to the hyalin substance 
of the ganglion cells, and, indeed, I suppose it to be the same, 
though one, certainly, a priori, may feel disposed to suppose 
myeline, or a similar substance, also to be present, even, if not in 
the way supposed by Rawitz, i. e. dififusively extended in the meshes 
of the net-work described by him and Haller. 
Of the structure of this central »Nervennetz« he gives a de- 
