MOVEMENTS OF VOLUNTARY MUSCLE. 
481 
quite entire, and seemed without disease, but no trace of fibrillse could be discerned 
on the closest examination. In fact, the sheath of the fasciculus was the only part 
remaining, the rest having probably become the food of these entozoa. As both ends 
of the tube remained open, having been broken off, several of the worms escaped from 
their confinement, and began to show signs of life, uncoiling themselves, and moving 
about slightly in different directions, with an undulating motion (fig. 42.). They 
were about ^th of an inch in length, blunt at one end, and tapering considerably 
towards the other. They contained in their interior numerous detached dots or gra- 
nules, of different sizes, but without the appearance of complicated structure, and 
there were no orifices detectable on their surface (figs. 42. 43.). Among the extruded 
worms there were many globular or oval bodies, nearly as large as one of the coiled 
parasites, and marked like them with minute dots. Some of these were evidently 
worms very compactly coiled, but in others no coils could be distinguished. These 
were smaller, invested by a very delicate membrane or cyst, having the appearance 
of immature animals (figs. 44. 45.). The whole number of worms in the sheath, I 
found to be more than 100. No other fasciculus was discovered in this state, but 
owing to want of time, a strict search was not made. Having previously examined 
minutely several recent examples of the Trichina spiralis, the well-known microscopic 
entozoon of voluntary muscle, the analogy in form, size and situation, between that 
and the one now described, at once struck me ; but the following points of difference 
will be immediately perceived. The Trichina spiralis lies in the cellular membrane 
among the fasciculi, always external to the sarcolemma , occupying a cell formed 
around it by the vital actions of the creature which it infests. Moreover, it is always 
solitary. On the other hand, this internal Trichina being within the sarcolemma, is 
entirely unconnected with vascular or cellular parts, is not confined by a cyst, but by 
the unaltered sheath, and it is gregarious. No artificial method of preparation could 
more convincingly have proved the toughness and comparative indestructibility of the 
sarcolemma, than this remarkable morbid condition, accidentally met with. 
I have ascertained the existence of the sarcolemma in Insects, Crustacea, Fish, Reptiles, 
Birds and Mammalia, and have so seldom failed to demonstrate it at pleasure in any 
of these classes, that I assume it to be an essential part of the composition of the fas- 
ciculi in all animals belonging to them. In some, it is more readily made apparent than 
in others, and by different methods of procedure, but by one or all of the modes of 
demonstration above enumerated, there is abundant evidence of its existence in all. 
The elevation of it by water, pressed out during contraction, may be witnessed in all 
these classes without exception. In the human subject, the sarcolemma is formed as 
early as the period of birth (fig. 30.). The striae are then strongly marked, and the 
fasciculi are in such a state of development as to be capable of performing motions 
of considerable extent. From this early epoch I have traced this structure at various 
ages, and in both sexes, to old age, when the atrophy of the muscles has often seemed 
to render it more easy of detection. It also remains in muscles wasted by disease or 
MDCCCXL. 3 Q 
