- 6; - 
the old physiological view of the function and combination of the 
nervous elements has brought histologists. 
Rawitz divides the ganglion cells according to their processes 
into different kinds, as this, however, in my opinion, is of but little 
importance I shall pay no further attention to it here. This much I 
shall only say, that, what he calls »Schaltzellen« — which are mul- 
tipolar cells having only »protoplasmic processes « (cfr. sequel) and 
situated only in the central »Nervennetz« ^) — are in my opinion 
not at all ganglion cells, but cells belonging to the neuroglia. 
Rawitz denies the presence of any connective tissue inside the 
outer neurilem-sheath ; this is the more surprising as on the one 
hand neuroglia-cells, according to my investigations, occur in great 
number in MoUuscs, and on the other hand he himself, besides the 
»Schaltze]len« above quoted, describes (p. 422) and illustrates (fig. 79) 
some, in his opinion, remarkable corpuscles from the cerebral gang- 
lia of Unio pictorum and Anodonta anatina. He has not been able 
to understand the significance of these corpuscles; he calls them 
»geschwånzte Kerne«. I do not think there can be much doubt, 
but that they are the cells which Buchholz has also mentioned, and 
which I describe as neuroglia-cells in the »dotted substance«. They 
have, certainly, quite the same appearance and shape. 
Rawitz describes numerous direct combinations between the 
ganglion cells of different kinds. These statements are, however, of 
but little importance to me, all much the more that Rawitz has not 
employed for his investigations lenses of very high powers or ho- 
mogeneous immersion ; his observations cannot therefore be considered 
as quite reliable in all respects, and especially not in these, where 
the best lenses are decidedly quite necessary, if you are to obtain 
a position to be able to state anything with certainty. 
The processes of the ganglion cells have, according to Rawitz, 
numerous »varikose Anschwellungen«, from which extremely slender 
fibrillæ very often issue. 
The cell-processes he divides into three kinds according to 
their course: 
1) „Stammfortsåtze'% »die direkt und stets ungetheilt zum peri- 
pheren Nervenstamm gehen.« 
2) „Mar7c fortsatte" which penetrate into the »Marksubstanz<!:, 
and are, there, broken up into fine fibrillæ. 
^) »In welches sie eingeschaltet sind, um es in seiner Funktion zu verstarken, 
und das sie mit ihren Fortsåtzen bilden helfen.« 
5* 
