Dr. Beale, on Sarcolemma, 
97 
common silkwormj if care be taken to prepare the specimens 
according to the principles I have laid down."^' 
The facts have an important hearing upon the question of 
the precise nature and origin of the nuclei which exist in 
connection with^ or external to^ the sarcolemma ; but it must 
be borne in mind that the number of these nuclei is very 
different in the sarcolemma of different animals. Thus, in 
some cases the membrane seems to be entirely destitute of 
nucleij while in other instances a vast number of nuclei 
exist. 
The matter is rendered still more difficult of explanation 
by the fact that the nuclei seen in connection with the 
sarcolemma have a different origin in different cases. If the 
muscular fibres of the white mouse be examined after the 
application of the acetic acid_, the observer would conclude 
that the sarcolemma contained a vast number of nuclei 
imbedded in its structure. If he were to examine the 
specimens more attentively, he would notice that in many 
cases nuclei followed each other as if arranged in a line, and 
he would further notice that these lines crossed the muscular 
fibre in different directions, some passing transversely, some 
obliquely, while some pursued for a short distance a longi- 
tudinal course. It is not possible to arrive at the explanation 
of these appearances, unless a specimen obtained from an 
animal the vessels of which have been minutely injected, 
and the nuclei of the tissues successfully stained with carmine, 
be examined after soaking in glycerine or syrup. The real 
meaning of the nuclei can, however, then be readily and 
positively determined. It becomes at once evident that 
the nuclei seen upon the surface of the elementary fibres are, 
for the most part, the nuclei of vessels and nerves. These 
structures (vessels and nerves) are so freely distributed upon 
the surface of the muscular fibres of this animal that the 
sarcolemma appears as a nucleated membrane in specimens 
which have been treated by acetic acid or potash. That they 
lie external to the sarcolemma is proved by the fact that 
they may be stripped off from the surface of this membrane. 
For representations of the vessels and nerves distributed to 
the elementary muscular fibres of the white mouse, see 
also my paper in the ^ Phil. Trans.^ for 1860, pi. xxiii, figs. 5, 
6, 7, and ^ How to Work with the Microscope,^ third edition, 
pi. xxvii, page 76. 
Now, at the spot where a bundle of fine nerve-fibres is 
about to divide into smaller bundles, to be distributed to the 
elementary muscular fibres, there is, of course, a large collection 
-* See * How to Work with the Microscope,' 3rd edition, p. 205 et seq. 
