NERVOUS FIBRES. 151 



that is, surrounded with a sheath, but naked, being transparent, 

 almost gelatinous, 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. ct microsc. de system, nervos. structura. 

 Berol., 1838, p. 5.) 1 



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. Thev 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. (PI. Ill, 

 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 pi. IV, fig. 

 8, a b. 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 



1 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 wen' nodulated at different 



spots, and which I discovered in the mesentery of frogs. No doubt they were or- 

 ganic fibres. 



