FIBRILS: FIBRES. 37 



(fig. 14), or osseous, or, as in fibro- cartilage, resembles fine 

 fibrous tissue (fig. 15). In some cases, the cells are very 

 loosely connected with the intercellular substance, and 

 may be nearly separated from it, as in nbro-cartilage : 

 but in some their walls seem amalgamated with it. 



The foregoing may be regarded as the simplest, and the 

 nearest to the primary forms assumed in the organization 

 of animal matter ; as the states into which this passes in 

 becoming a solid tissue living or capable of life. By the 

 further development of tissue thus far organized, according 

 to rules which will be hereafter described, higher or 

 secondary forms are produced, which it will be sufncient 

 in this place merely to enumerate. Such are, 



4. Filaments, or fibrils, Threads of exceeding fineness, 

 from -gooooth of an inch upwards. Such filaments are 

 cylindriform, as are those of the striated muscular and 

 the fibro-cellular or areolar tissue (fig. 8); or flattened, as 

 are those of the organic muscles. Filaments usually lie 

 in parallel fasciculi, as in muscular and tendinous tissues ; 

 but in some instances are matted or reticular with branches 

 and intercommunication, as are the filaments of the middle 

 coat, and of the longitudinally -fibrous coat of arteries ; and 

 in other instances, are spirally wound, or very tortuous, as 

 in the common fibro-cellular- tissue (fig. 9). 



5 . Fibres, in the instances to which the name is commonly 

 applied are larger than filaments or fibrils, but are by no 

 essential general character distinguished from them. The 

 flattened band-like fibres of the coarser varieties of organic 

 muscle or elastic tissue (fig. i o) are the simplest examples 

 of this form ; the toothed fibres of the crystalline lens are 

 more complex ; and more compound, so as hardly to permit 

 of being classed as elementary forms, are the striated mus- 

 cular fibres, which consist of bundles of filaments enclosed 

 in separate membranous sheaths, and the cerebro-spinal 

 nerve-fibres, in which similar sheaths enclose apparently 

 two varieties of nerve substance. 



