MUSCLE ; NERVE 



1051 



especially found in the walls of the stomach, intestines, bladder, and 

 other similar parts, is composed of flattened bands whose diameter is 

 usually between ^uWth anc ^ ToVo^h f an i ncn ; an d these bands are 

 collected into fasciculi, which do not lie parallel with each other, but 

 cross and interlace. By macerating a portion of such muscular sub- 

 stance, however, in dilute nitric acid (about one part of ordinary 

 acid to three parts of water) for two or three days, it is found that 

 the bands just mentioned may be easily separated into elongated fusi- 

 form cells, not unlike * woody fibre ' in shape (fig. 787, a a) ; each 

 distinguished, for the most party by the presence of a long staff- 

 shaped nucleus, b, brought into view by the action of acetic acid, c. 

 These cells, in which the distinction between cell- wall and cell-con- 

 tents can by no means be clearly seen, are composed of a soft yellow^ 

 substance often containing small pale granules, and sometimes yellow 

 globules of fatty matter. In the coats of the blood-vessels are found 



FIG. 787. Structure of non-striated 

 muscular fibre : A, portion of 

 tissue showing fusiform cells a a, 

 with elongated nuclei b b ; B, a 

 single cell isolated and more 

 highly magnified ; C, a similar 

 cell treated with acetic acid. 



FIG. 788. Ganglion-cells and nerve- 

 fibres from a ganglion of lamprey. 



cells having the same general characters, but shorter and wider in 

 form ; and although some of these approach very closely in their 

 general appearance to epithelium-cells, yet they seem to have quite 

 a different nature, being distinguished by their elongated nuclei, as 

 well as by their contractile endowments. 



Nerve-substance. Wherever a distinct nervous system can be 

 made out, it is found to consist of two very different forms of tissue, 

 namely, the cellular, which are the essential components of the 

 ganglionic centres, and the fibrous, of which the connecting trunks 

 consist. The typical form of the nerve-cells or ' ganglion-globules 

 may be regarded as globular ; but they often present an extension 

 into one or more long processes, which give them a ' caudate ' or 

 ' stellate ' aspect. These processes have been traced into continuity, 

 in some instances, with the axis-cylinders of nerve-tubes (fig. 788) ; 

 whilst in other cases they seem to inosculate with those of other 



