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GENERAL PRINCIPLES OF ZOOLOGY. 



branched connective-tissue corpuscles (Fig. 38). In the 

 vertebrates, numerous fibres unite into a bundle; each 

 bundle is generally surrounded by connective-tissue cor- 

 puscles, metamorphosed into flat cells. The bundles, irregu- 



FIG. 38 Fibrous connective tissue of an 

 Actinian. 



FIG. 39. Areolar fibrous connective 

 tissue. (After Gegenbaur.) 



larly interwoven, run in all directions (areolar connective 

 tissue, "cellular tissue" of the earlier authors) (Fig. 39), 

 or, again, they may be arranged almost parallelly and form 

 a compact mass of fibres (tendinous tissue) (Fig. 40). Since 

 the fibrils of the fibrous connective tissue of the vertebrates 

 have another peculiarity not elsewhere met with, in that 

 they are composed of albuminoids (elastin and collagen), 

 and upon boiling become glutin (gelatine, glue, etc.), it is 

 proper to reserve for these forms of tissue the special name 

 " connective tissue." 



Elastic Tissue. In all fibrous connective tissue there 

 may appear, as a further constituent element, elastic 

 fibres; they may indeed supplant the ordinary connec- 

 tive-tissue fibrils and become the predominant element of 

 the connective tissue, which is then spoken of as elastic 

 tissue. 



Cartilage. Cartilage and bone are likewise tissues 

 which find their characteristic development only in the ver- 



