16 
W. J. Dakin 
deeply staining, separated by passages where the fibrillae appear to run 
more in the plane of the section and from right to left. These structures 
were seen by Rawitz whose description is so remarkable that it is almost 
impossible to believe that it has been written with reference to more 
than one section, and that an oblique one. He states (1887 pag. 59) that 
the lateral lobes fall into two sharply divided parts, an anterior quarter 
and a posterior three-quarters. The central mass of the former is called 
the »spongiöse Substanz«. In this substance are no nerve cells, nor 
»Schaltzellen« and it is to be distinguished from the Marksubstanz 
(Neuropil) by its appearance "Denn während letztere das bekannte zen- 
trale Nervennetz bildet, hat erstere keinerlei Andeutung davon, viel- 
mehr erscheint sie bei starken Vergrößerungen (fig. 86) wie durchsetzt 
von feinen, kaum punktförmigen Löchern und gewinnt dadurch das 
Aussehen eines sehr feinporigen Badeschwammes". The »spongiöse 
Substanz« falls into groups (the rounded areas previously mentioned) 
which according to Rawitz number from 2 — 4 in the right lobe and 
5 — 14 in the left. The posterior three-quarters is called the »retikuläre 
Substanz «. 
This description of Rawitz agrees perfectly with his figure, which 
again resembles a low power view of a section which has cut the central 
mass of fibres in the anterior quarter of the lateral lobe, but has been 
sHghtly oblique and hence run exactly through the cortical layer of ganglion 
cells for the remaining three-quarters of its course. There is no diffe- 
rence whatever in the structure of the lateral lobes from the anterior to 
the posterior end. The areas of so-called »spongiöse Substanz« occur in 
the same way to the posterior end and the only structures which in any 
way resemble the region of the »retikuläre Substanz« in Rawitz' figure 
are cross sections of the cortical layer of cells. 
In sections cut in the plane of the ganglion the areas of so called 
»spongiöse Substanz« (fig. 4 s) do not differ very much from the central 
neuropil. They are distinct because in the first place they stain darker, 
and secondly because they are very definitely bounded by fibres running 
in a direction from right to left. They appear themselves to consist of 
a mass of very fine neurofibrillae either simply interwoven or more pro- 
bably forming a net, and the darker staining is due to the compactness 
of the structures, for the Spaces between the fibrillae or the meshes of 
the net are exceedingly small. There are twenty or more of these areas 
in the left lateral lobe and 5 — 14 in the right. Vertical sections through 
the lateral lobes (fig. 3) solve immediately the problem of the areas of 
»spongiöse Substanz«. It will be seen from the figure that a number 
