— 114 — 
' Lumbricus agricola. 
The ganglion cells of Lumbricus are, in their structure, somewhat 
similar to those of Nereis. In sections, their protoplasm has a distinct, 
reticular, granulous appearance; large granules, similar to those found 
in the ganglion cells of Nereis, do not, however, occur. The whole 
protoplasm is, in preparations, rather deeply stained; the reticulation is 
generally very distinct, slight thickenings are only seen in the points 
where the walls of the meshes unite. The meshes are generally 
very large; that they are, at all events to a great extent, really 
transsected tubes is, I think, clearly seen in fig. 47, which represents 
a section through a large ganglion cell, and which is drawn under 
the camera lucida as exact to nature as possible (very highly magni- 
fied). The tubes are, in this illustration, seen transversally as well 
as partly longitudinally transsected, giving, the protoplasm to some 
extent, a concentric appearance; the tubes forming the nervous 
process are seen to be quite like those circulating in the protoplasm.^) 
In some cells, a kind of higher differentiation seems to be pre- 
sent in the protoplasm ; such a cell is represented in fig. 46. Lighter 
fein granulirten Kern und dieser ein einzigcs grosses Korperchen.« A similar dif- 
ference in the appearance of the small and large ganglion cells is, certainly, very 
prominent also in the nervous system of Ne7'eis ; but as I have found transition forms 
between both these kinds of cells, I can not distinguish between two types. My 
experience is to some extent that, the larger the cells are, the more and more 
granular become their protoplasm, and there can not easily be drawn any line of 
demarcation. 
As to the sheaths of the ganglion cells BoJide says : »Beide Ganglienzellen- 
arten entbehren einer Zellenmembran und liegen eingebettet in ein Maschenwerk 
von Fasern, welche iiberall das Nervensystem begleiten und, wie ich glaube, aus 
Subcuticularzellen hervorgegangen sind.« As may be seen from my description I 
agree with this statement of JRoJide; his »Fasern« or »Subcuticularfasern« belong 
to what I call the neuroglia. 
Of the protoplasm of the largish cells jRohde says: «dass die ganze Zelle 
nach allen Richtungen von veschieden starken Faserchen durchzogen wird, welche 
auf den Zellfortsatz tibergehen und diesem eine feine Langsstreifung verleien. Aber 
nicht nur hier verlassen diese Faserchen die Zelle, sondern man ist iiberrascht zu 
sehen, wie sie theils einzeln, theils zu Biindeln vereinigt allenthalben an der Peri- 
pherie des nackten Zellkorpers heraustreten und in die Subcuticularfaserhiille ein- 
dringen.« It is evident that JRohde and I have observed the same structures ; his 
»Fåserchen« must partly be what in my opinion are the spongioplasmic sheaths of 
the primitive tubes (especially those which pass into the nervous process), and the 
«Faserchen» penetrating in the Subcuticularfaserhulle« must be the spongioplasmic 
fibres issuing from the neurogUa-sheath of the cell (vide hg. 44, 5/"; fig. 451*'/"; ^ig 67)- 
and v/hich fibres partly form a spongioplasmic reticulation in the protoplasm (com- 
pare my description of Homarus p. 10 1). 
\) The tubes in the protoplasm seem to be of different size in the various cells. 
