KOLLIKER, ON MUSCULAR FIBRE. 5p 
frog, that, viz., acccording to which each muscular fibre is pro- 
duced from a single cell, which becomes exceedingly elon- 
gated, did not apply to the case of ail transversely striated 
fibres (‘ Wiirz. Verh.’ viii. p. 113). Iam now, in fact, enabled 
to show that the same mode of formation also obtains in the 
human subject. In a two-months embryo I found the 
muscles of the rudimentary foot in so undeveloped a condi- 
tion, that it was by no means difficult to exhibit their very 
early conditions. The earliest forms seen by me were simple 
fusiform cells, 0‘06—0°08” long containing in the middle por- 
tion, which was 0:001—0'015” in breadth, one or two elongated 
nuclei, and produced at either extremity into an extremely 
delicate filament at most 0:0004” im diameter, presenting at 
the same time no trace of transverse striation. Now from 
the muscular substance of the thigh and leg a complete 
series of forms, from these simple fibre-cells, which could be 
nothing else than elongated primordial embryo-cells, could be 
traced up to fibres 0°2—0°3” long and 0:002” wide, which were 
also attenuated at each end, and containing 4—9 elongated 
nuclei placed at considerable distances apart, and also pre- 
senting the first faint indications of a transverse striation, so 
that it could not be doubted that the future muscular fibres 
are derived simply from a growth in length and breadth of 
the original uninucleated fibre-cells, accompanied with an 
energetic multiplication of the nuclei; to which growth is 
subsequently superadded a peculiar transformation of the cell- 
contents. And this conclusion was the more readily arrived 
at from the circumstance that the nuclei of these elements 
presented almost all the indications of an active multiplica- 
tion, which I have already described. 
I am convinced that in more advanced embryos the 
pointed extremities of the muscular fibres will also be found ; 
and it would also, as it seems to me, appear that these ob- 
servations explain the recent discovery by A. Rollett of the 
occurrence of numerous free, pointed extremities of the mus- 
cular fibres in the adult. 
If in the frog and in man the muscular fibres represent 
simple vastly enlarged cells—which, it may be remarked, is a 
strong proof of the active formative capacity of the animal 
cells—it can no longer be doubted that the same holds good 
of all transversely striated muscular fibres, nor in future can 
any distinction be drawn between contractile fibre-cells and 
muscular fibres as representing numerous cells. Certain 
distinctions will in all cases remain, with respect to which I 
would at present remark that the circumstance whether the 
