i04 
Dr. Beale, on Sarcolemma. 
not be much stretched or compressed. If this contrac- 
tile material is not thus removed from beneath the sar- 
colemma_, the numerous dark lines caused by the trans- 
verse striae of the muscle necessarily prevent the far more 
delicate lines caused by the finest tracheae and nerve-fibres 
ramifying upon the sarcolemma from being seen. Such 
an accident not unfrequently happens in the preparation of 
specimens from the maggot. One instance in which the 
arrangement about to be described was remarkably distinct 
is represented in PL XIV, fig. I, in which, also, the general 
mode of ramification of muscular nerves is represented."^ 
It will be observed in this specimen that one fine branch of 
the bundle of nerve-fibres traversing the muscle, after passing 
a short distance from the trunk, seems to cease abruptly upon 
the sarcolemma. Although I shall describe the arrangement 
of this one fibre, it must not be supposed that this is the only 
fibre distributed to this muscle, for many fine branches reach 
the sarcolemma at other points from diff'erent nerve-trunks. 
The mode in which the terminal branch leaves the nerve-trunk 
is represented in fig. 3. At this spot three sets of nerve- 
fibres, passing in three diff'erent directions, will be noticed. 
One set takes the course of the original trunk, and is not 
concerned in the formation of the terminal branch. The two 
other sets, coming from opposite directions, unite to form the 
fine compound bundle, the further ramification of which will 
be considered presently. I have already drawn attention to 
this peculiar arrangement of nerve-fibres at the point where a 
branch leaves the nerve-trunk, and have stated that it is to 
be observed in connection with all nerves of all animals. (See 
my ^ Archives,^ No. XIV, page 127.) 
The point where the fibre in fig. 1 seems to be lost on the 
surface of the sarcolemma is represented magnified nearly 
3000 diameters in PL XV, fig. 3. The fine trunk is com- 
pound, and, instead of consisting of a single nerve-fibre, as 
represented in some of Kiihne's drawings of insect-nerve, 
really consists of a number of exceedingly delicate nerve- 
fibres, each one of these being composed of still finer fibres, 
which divide and subdivide very freely^ forming an elaborate 
network, which may be traced over every part of the sarco- 
lemma. In some places the meshes formed by the ramifica- 
tion of the nerve-fibres are much smaller than in others. 
In fig. 8, a very fine nerve-fibre, dividing into numerous 
branches, and forming a network or plexus, is represented. 
And in figs. 4, 5, 6^ are some other portions of the nervous 
network. 
* Por a description of this figure see the * Explanation of the Plates.' 
