480 
MR. BOWMAN ON THE MINUTE STRUCTURE AND 
and it is in the Frog and Newt that I have found it to be most conveniently witnessed. 
A few fasciculi laid on glass are separated by needles, wetted, and covered with mica. 
They are then ready for inspection with a high power. Water is taken up into their 
structure, and their irritability being still retained, and perhaps excited by the dis- 
tension of the water, the fibrillse begin to contract. By the contraction the water is 
pressed out forcibly from among them, and their mass diminishes in bulk ; the fluid 
at the same time accumulating at their surface between them and the sarcolemma. 
The membrane is thus bulged and torn up more or less extensively from its connec- 
tions with the fibrillse (figs. 47. b. and 71 to 79.). The process may be frequently 
watched in its whole course ; the contraction of the fibrillse is the first step, and as 
this proceeds the sheath is seen to be elevated a little from their surface, at first in 
small sudamina-like vesicles. By degrees these increase and coalesce with more or 
less facility, sometimes subsiding in one part to rise larger in a contiguous one. These 
slighter and earlier stages of the phenomenon are best seen at the margin of the fas- 
ciculus, where a profile view is obtained ; but when the changes are more decided, or 
indeed even when they are but trivial, provided the eye is prepared to detect them, 
they may be discovered on the surface next the observer : and generally, the folds of 
the sarcolemma occasioned by a large bulla visible at the margin are traceable for 
some distance over the proximal surface. In such a case the fibrillse and their strise 
are beyond the range of the focus in which the sarcolemma is apparent. Sometimes 
the fluid is expressed in such quantity, as to separate the tunic completely from the 
fibrillse for some length, a circumstance which becomes especially notable when the 
specimen is accidentally bent, for the fibrillse then take the shortest course along its 
concavity, the distended membrane forming the convexity of the curve at a consider- 
able distance. The whole sarcolemma thus assumes the appearance of a crystal tube, 
filled with a transparent fluid, immersed in which the fibrillse pursue their course as 
a contracted bundle. 
Lest it should be imagined that the fluid forming these bullse is a normal consti- 
tuent of the fasciculi, I may observe that none are developed on contracting muscle, 
when either unwetted, or immersed in a medium of some density, as syrup. Bullse 
already formed are immediately removed by the presence of syrup, which absorbs 
their water, and yet I have sought in vain in uncontracted fasciculi placed in syrup 
for any appearances of shrinking, which would necessarily present themselves did a 
fluid of so little density exist naturally among any interstices of the fasciculi. 
There is another illustration of the existence and qualities of the sarcolemma , which 
seems of so novel and interesting a character, that I cannot refrain from mentioning 
it. In an Eel, which to all appearance was in perfect health, and contained as usual 
among its muscles, a considerable quantity of fat, one fasciculus of the same size as 
the rest, instead of presenting the muscular substance, was reduced to a mere dia- 
phanous tube, containing a number of minute parasitic worms, coiled up like the 
Trichina spiralis, and closely packed together (figs. 41 to 45.). The sarcolemma was 
