MULTIPLE NEUROMATA OF THE CENTRAL NERVOUS SYSTEM. 701 
fibrils of Apathy and Bethe) and interfibrillar substance (the axoplasm of Schieffer- 
decker). Between axis-cylinder and myelin is a thin zone of undifferentiated proto- 
plasm, which ScHIEFFERDECKER regards as a peri-axial lymph-space. 
The myelin is composed of protoplasm of specific characters and is constituted by a 
“network of neuro-keratin, whose meshes contain a phosphorised fat. The continuity 
of the myelin is broken by oblique notches arranged in an imbricated manner, the 
incisures of Lantermann, which stain by Strahiiber’s method similarly to the axoplasm 
of Schiefferdecker and probably represent a portion of the undifferentiated protoplasm. 
Some observers, however, look upon both incisures and network as artefacts, others 
regard them as a stage in the evolution of the nerve fibre 
as they are much more 
evident in the early stages of development, and still others compare them to the canals 
‘met with in other cell protoplasms. According to SCHIEFFERDECKER and DuRANTE, 
both incisures and network are present in the fibres of the central nervous system. 
The sheath of Schwann is the thin condensed outer border of the protoplasm of the 
‘interannular segment. It is often difficult to distinguish it from the endoneurium 
which surrounds each individual nerve fibre. he nucleus of Schwann is the nucleus 
of the original cell lying in a thin zone of undifferentiated protoplasm in which, 
early stages of development, fine granules, comparable to Nissl’s granules in the nerve 
cell, can be recognised. 
Remains of undifferentiated protoplasm are thus found in the interfibrillar substance 
of the axis-cylinder, in the periaxial zone, in the incisures of Lantermann, and in the 
perinuclear zone. It is the nucleus and this undifferentiated protoplasm which increase 
‘so greatly in pathological conditions. 
A nerve trunk is surrounded by a connective-tissue envelope, the epineurium, and 
around each funiculus is the perineurium. The endoneurinm passes between the 
nerve fibres of the funiculus, and its finest ramifications, lined by flattened endothelial 
cells, form round each nerve fibre a fibrillar network (the sheath of Henle). 
_ Duranre has also emphasised the complete analogy, according to this view, between 
muscle and nerve elements. The muscle fibre consists of (1) myoplasm—the fibrillar 
contractile substance,—which is a product of the internal differentiation of the sarco- 
plasm, (2) the remaining undifferentiated sarcoplasm, (3) the sarcolemma, the condensed 
outer layer of the non-differentiated sarcoplasm, with (4) its peripherally placed sarco- 
lemma nucleus in a thin zone of undifferentiated protoplasm. Under normal conditions 
the differentiated substance greatly preponderates over non-differentiated, but in patho- 
Jogical conditions the differentiated substance degenerates and the nucleus and non- 
differentiated substance take on a vegetative rdle and return to their embryonic 
condition. 
