440 Prof. G. Retzius. Principles of the [June 15, 
the periphery is the intracellulur fibril network itself. He has shown that it 
is formed very early in a special part of the nerve-cells (neuroblasts), subse- 
quently growing towards the periphery (and towards the centre) along the 
previously formed paths. He maintains also that there are a large number 
of anastomoses between the special nerve-cells, and even between their 
processes; these he calls newrodesms, and says that the fibrils in them are 
able to grow from one neurone to another; in that way a large anastomosing 
fibril network might arise in the organism, somewhat similar to the one 
Apathy has proclaimed. 
In a criticism of this theory of Held’s, which Cajal published recently, he 
showed forcibly its inadmissibility. For my own part I must join Cajal in 
his estimate of this attempt of Held’s to alter the neurone theory. However, 
I have no opportunity now of entering into a further discussion of the matter, 
and so must only refer to Cajal’s critique. , 
In addition to the researches, the progress and present results of which I 
have here endeavoured to give a brief sketch, there are a few other branches 
of this extensive field of work that are of great importance for the science of 
Neurology, which, however, the time at my disposal does not permit me 
more than briefly touching upon. 
One of these lines of investigation is directed towards finding out 
accurately the finer structure of the cortex substance and the nuclei of the 
inner ganglia of the brain, with special attention to the exact discovery of 
the characteristic structure of each several part of it. In this inquiry the 
aim has been first and foremost to find the distinguishing marks of the 
different centres in the brain cortex, in accordance with what Physiology 
teaches us. There came first some few scattered observations of a tentative 
nature, then, above all, Meynert’s subdivision of the brain cortex into five 
strata on the basis of the differing constitution of the nerve-cells, Betz’s 
discovery of the large pyramid cells, and Bevan Lewis’s analysis of their 
occurrence, which also embraces investigations of Gyrus hippocampi and its 
special construction. In 1893 the Swedish neurologist Carl Hammarberg, 
whose early death was a real loss to science, published the results of his 
systematically conducted studies upon the cortex substance of the human — 
brain, and thereby paved the way for a more exact special investigation into 
this important department. Golgi, Kaes, and others carried the inquiry still 
further, but it was reserved for Cajal to effect a real enrichment of our 
knowledge in this direction as a result of his subtle and accurate researches. 
The work done by Cajal has also brought to light many important points 
regarding structure in respect to the ganglia of the brain, as has that of 
v. Kolliker, of Van Gehuchten, and of several other scientists, but in those 
