1793 

answered. At the best the solution is exceedingly difficult. The 
delicacy of the cell wall, the overlying or underlying of it by muscle 
fibrillae, granulae, and telophragmata, all add to the difficulty in 
answering the question. The middle of the three muscle cells in 
fig. 1, however, possibly presents evidence upon which a correct 
conclusion may be drawn. The uppermost pole of this cell demon- 
strates what appears to be the reflected edge of the cell wall. The 
instance is not exceptional, since many such appearances are demon- 
strable throughout the entire series of sections. But the possibility 
of its being an obliquely-sectioned cell extremity together with the 
difficulties enumerated above render, with 
our present microscopical technic, a posi- 
tive answer most injudicious. 
Two muscle fibres, represented as 
transversely sectioned, are seen in figure 2. 
A blood vessel occupies the angle between 
them. Each fibre presents a muscle cell. 
That on the left was encountered at the 
level of the middle of the nucleus; that 
on the right above the level of that 
structure. In the latter the structure of 
the cell protoplasm is in marked contrast 
to that of the sarcoplasm. The presence 
of a cell wall separating the two is un- 
questionable. The spongioplasm network 
of the cell is relatively heavily laden 
with granules. Notwithstanding, the clear 
fibrillae of this network can in many 
levels be traced directly up to the internal surface of this cell wall 
upon which they end. They do not at any place find an insertion upon 
the muscle fibrillae. A narrow interval of sarcoplasm, equal in general 
to the cross-diameter of an average muscle fibril, intervenes between 
the latter and the cell wall. 
The cell on the left is of interest chiefly because it demonstrates 
appearances comparable to those observed in connection with similarly 
cut sections of voluntary striped muscles. The remarks made in the 
cited articles regarding such appearances apply here as well. At 
such levels the membrane appears to be wanting, i. e., the nucleus 
seems to be immediately imbedded in the sarcoplasm. Hence the 
12* 
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