— 149 — 
combination upon the whole exists between the ganglion cells, then 
this combination must be produced by the nervous processes. That 
such a combination can exist, with the dotted substance as a medium, 
we will easily understand when we think of the course of the nervous 
processes. As is previously mentioned, there may be drawn a 
distinction between two types of ganglion cells in respect of the 
course of their nervous processes; viz. i) ganglion cells with nervous 
processes which directly hecome nerve-tuhes and thus do not lose 
their individuality, though they have no isolated course hut give ofl 
side-lranches to the dotted substance; 2) ganglion cells with nervous 
processes which lose their individuality and by subdivisions are 
entirely hroJcen up into slender hranches, losing themselves in the 
dotted substance. 
We have, thus, slender branches given off to the dotted sub- 
stance, by both kinds of nervous processes. What is to prevent 
these branches standing in communication with each other, seeing 
hat they are so intimately intermixed. Certainly, I have not been 
able to observe such a communication, but seeing how very intricate 
these structures are, we need scarcely at present expect to do so. 
In fact, I do not see any objection which can justly be made to a 
combination existing between the ganglion cells by help of the nervous 
processes and their branches. Still, I do not lay much stress upon 
such a combination existing, or not existing, as in a subsequent 
chapter will be explained; the principal question, in my opinion, is, 
how is the combination between the nerve-tubes produced. 
5. The nervous elements of Amphioxus and Myxine. 
Though I propose to reserve the nervous systems of Amjjhioxus 
and Myxine for a future special memoir, I will, here, for the sake 
of comparison, make some remarks on the structure of their nervous 
elements. 
Amphioxus lanceolatus. 
As is known from the descriptions of previous writers ^) the 
spinal cord of Amphioxus has, along the centre, a groove or 
canal extending from the dorsal side and surrounded by and epi- 
0 OivsjanniJcoiv (1. c. i868) and Stieda (1. c. 1873) may especially be men- 
tioned. I regret to say that I have had no access to Stieda'?, paper; I only know 
it therefore from the abstract of it in Hofmann's and Schwalbe's Jahresb. d. 
Anat. u. Phys. Bd. 2. 1875. 
