102 THE MICEOSCOPIST. 



&c.), have their fibres marked with transverse striae. The in- 

 voluntary muscles are not so marked. These marks are sup- 

 posed to point out the ultimate corpuscles or cells of which 

 the fibrillae are composed. The general opinion is, that the 

 juxtaposition of cells is the true form of the ultimate fibre. 

 Several microscopists, however, of some note, believe the fibre 

 to be spiral, and enclosed in a membranous sheath. Others 

 have thought the transverae striae to be due to a corrugation 

 of the fibre. In my own examinations I have met with cases 

 where the structure appeared to be a bead-like fibre wound 

 spirally into a tube, or around a central unmarked fibre ; yet 

 other observations, especially with polarized light,, show a lon- 

 gitudinal arrangement of cells. Perhaps the true structure is 

 a compound of both these modes; the sheath being spiral, and 

 the ultimate fibre longitudinal. If we should state that the 

 ultimate granules or cells of muscular substance are arranged 

 in fibres, and that a number of such fibrillae are enclosed in a 

 spirally corrugated sheath, a number of such bundles being 

 united together ; the description would correspond with the 

 majority of observations. 



A small portion of muscle, freed from cellular tissue, may 

 be put on a slide with some kind of fluid, placed under the dis- 

 secting microscope, and the fibres torn asunder with fine needles. 

 It should be preserved in fluid under a thin glass cover. 



The nerves of muscle may be displayed in a thin layer of 

 delicate fibres which form a part of the abdominal wall of a 

 frog, by employing a compressorium. The capillary blood- 

 vessels may be seen when injected. By the use of the com- 

 pressor, the thin recti muscles of the eyes of small birds, if 

 seen soon after death, will, without injection, show both nerves 

 and capillaries. 



NERVE. The dissection of nerves, to show their ultimate 

 structure, is similar to that of muscle, above described. It 



