HISTOLOGY OF THE STEIPED MUSCLE-FIBEE. 
379 
meshes are small, distinct thickenings or dots are seen at the 
intersections of the fibres composing the network. This net- 
work is particularly sharply defined and is plainly seen to be a 
true network^ that is, the lines represent linear fibres only. It 
is not a honeycomb work. The lines do not represent the 
edges of plates of interfibrillar material. 
(d) Crustacean. — An exactly similar network can be 
brought out in the muscle of the lobster. My friend Mr. C. 
F. Marshall has made preparations of lobster muscle with 
acetic acid and gold which show this network in a most 
beautiful manner. The muscle in this case was left in 15 per 
cent, acetic acid for fifteen minutes (a much longer time than 
I use), in gold chloride thirty minutes, and in 25 per cent, 
formic acid in a warm chamber for three hours exposed to the 
light. 
This network represents the transversely and longitudinally 
arranged network described in insects’ muscle pulled out of 
shape. In some of the fibres indeed it is still seen arranged 
in the rectangular manner. Fig. 8 represents a portion of a 
fibre in which transverse are crossed by longitudinal lines with 
dots at the intersections. In this case the ordinary light and 
dim transverse striation is obtained by refraction round the 
nodal dots. 
At first sight the meshes of the irregular network described 
in the frog and lobster look too large to correspond in size 
with the meshes of the horizontal network in Dytiscus, that is, 
with the end view of sarcous elements. But we must not 
forget the effect of pressure ; it expands the fibre to about ten 
times its normal diameter, and a corresponding increase in the 
size of the meshes takes place. Fig. 11 represents a transverse 
section of the fibre of the frog cut fresh with the freezing 
microtome and stained by the gold method. It has not been 
much enlarged by pressure and hence the meshes of the net- 
work are small. 
Fig. 10 represents a portion of a fibre of the lobster which 
has split into fibrils; an uncommon effect in gold preparations. 
