1908. | Minute Structure of the Nervous System. 433 
helonging to them. Thus, he alleged he had hereby clearly shown the 
small importance the ganglion cells have as regards the activity of the 
nerves. 
I have myself tried to carry out these experimenis of Bethe’s on my own 
account, but have come to the conclusion that it is practically impossible to 
operate with such precision on the semi-transparent and soft ganglions of 
the living animal (Carcinus menas) that a removal of some particular groups 
of cells will be certain to result. Under such conditions I consequently 
regard it as exceedingly unsafe to draw the conclusions Bethe has done. 
The question is fundamentally of such moment that the utmost caution is 
necessary in arriving at any conclusions at all. I, at any rate, after the 
experience [ have derived from my experiments, must call in question the 
certainty and accuracy of what he has stated as his conclusions. 
Now, however, a new epoch of neurological investigation was to be 
inaugurated, for Cajal and Bielschowsky almost simultaneously invented 
methods very similar to one another for staining the fibrils in the nerve-cells 
and their processes by means of a silver solution. That not only confirmed 
the existence of the neurofibrils seen by Apathy, but added very materially 
to our knowledge, especially of the nervous system of the higher animals, 
the vertebrata. Thanks to these methods, it was shown by the inventors 
themselves and by other investigators, who had taken up the study of these 
problems, that everywhere in the nerve-cells and their processes there exist 
fibrils which belong to the cell substance and are very early developed in 
it. Cajal proved, too, that these fibrils form reticula in the cells, and that 
they increase or decrease in thickness according to the state in which the 
animal is, different in health and sickness (e.g., rabies), etc. ; he also pointed 
out that in the cell processes these fibrils always remain within their 
substance, and are not, as Apathy asserts, capable of emerging from it. 
Cajal asserted also that the fibrils do not anastomose outside the neurones, 
and specially not in the central substance and in the Punktsubstanz. This 
important point, which entirely agrees with the results I obtained before by 
the methylene method, was confirmed by the new researches I carried out 
with Cajal’s new fibril staining method which gives a very full and distinct 
colouring to even the most delicate ramifications of the nerve-fibres (fig. 11). 
Now these form everywhere, even in the most successfully stained parts, in 
the Punktsubstanz of the invertebrata as well as in the grey substance of the 
vertebrata, not anastomosing reticula, but only twistwork (plexus); divisions in 
the fibres occur, but no network is visible. 
I call attention to this fact once more, since the question has an important 
