656 



APPENDIX. 



and a very small portion of the submucous tissue cut from the 

 edge of the tongue with a pair of sharp scissors. This is torn 

 into fragments with very fine needles, and then placed in the 

 field of a quarter-inch object-glass. . If the tongue is boiled 

 very long, the fibres become too brittle for separation and 

 examination. 



The Crustacea, moUusca, and insecta present peculiarities in 

 the structure of their voluntary muscular fibre which separate 

 them in a marked manner from the higher divisions of the 

 vertebrata. 



Fio. 349. 



The involuntary, smooth, or non-striated muscular fibres, 

 though appearing like flattened bands (Fig. 350), in reality, ac- 

 cording to Kolliker, consist of elongated cells. They are found 

 in various situations, as in the alimentary canal, the large and 

 small arteries, veins and lymphatics, the 

 trabecular tissue of the spleen, the uterus, 

 bladder, and urethra, &c. 



" The contractile fibre-cells have been 

 arranged in three classes : — 



1. Short rounded or flattened cells, 

 somewhat resembling epithelium. 



2. Flattened bands, with fringed edges. 



3. Long rounded or fusiform fibres, 

 slightly wavy, and terminating at each 

 end in a point. 



Fig. 351. 



" The first two varieties are obtained from the bloodvessels. 

 The last form is met with in the intestinal canal, uterus, &c. 

 These cells may be readily isolated by macerating small pieces of 

 the muscular coat of the alimentary canal, &c., in dilute nitric 

 acid, containing about 20 per cent, of strong acid. By a little 



