NERVOUS FIBRES. 151 
that is, surrounded with a sheath, but naked, being transparent, 
almost gelatious, and much more minute than most of the 
primitive tubes. They almost always exhibit longitudinal lines 
upon their surface, and readily separate into very minute fibres. 
In their course they are very frequently furnished with oval 
nodules, and covered with certain small oval or round, more 
rarely irregular, corpuscles, which exhibit one or more nuclei, 
and in size almost equal the nuclei of the ganglion-globules.” 
(Observationes anat. et microsc. de system. nervos. structura. 
Berol., 1838, p. 5.)' 
These corpuscles may at once be recognised, both in Remak’s 
delineations, and when examined in the natural state, to be cell- 
nuclei, which are round or oval, and frequently furnished with 
one or two nucleoli. They are attached to the most minute fibres, 
and as they are thicker than the fibres, they often appear to be 
situated only on their outside. Observation, however, does 
not warrant the conclusion that such is actually the fact. In 
the secondary muscle-cells (in which the nuclei decidedly lie 
within the cell) it frequently appears, and especially in the 
later periods of development, previous to the disappearance of 
the nuclei, as if the nuclei lay externally to the cell, inasmuch 
as they become pushed towards the outside. But no doubt 
the cell-membrane is at the same time elevated upon them, as 
we saw to be so distinctly the case in the fat-cells. (Pl. ITI, 
fig. 10.) Now, these most minute organic fibres, furnished 
with nuclei, precisely resemble the earlier condition of the 
white nervous fibres, as they were represented in pl. IV, fig. 
8, a 6. Both have the same pale, minutely-granulated ap- 
pearance, and both present cell-nuclei in their course. The 
only difference is, that the organic fibres are much more 
minute and the nuclei smaller. Each single nucleated or- 
ganic fibre (I do not mean an entire fasciculus of them) cor- 
responds to a white primitive fibre, and is probably, like it, a 
secondary cell, which has been generated by a coalescence of 
primary cells, whose nuclei are the nodules described by 
' Remak’s discovery of the peculiar structure of the organic nervous fibres ex- 
plains an observation previously communicated by me upon some extremely minute, 
pale, nervous fibres, which did not appear tubular, and were nodulated at different 
spots, and which I discovered in the mesentery of frogs. No doubt they were or- 
ganic fibres. 
