1 6 Introduction to Animal Morphology. 



cellular structure may be white, inelastic, containing mucin, 

 acted on by heat, acetic acid, and liquor potassae ; or yellow, 

 elastic, and resisting most reagents. The white form exists 

 in tendons, fasciae, ligaments, the basement of serous mem- 

 branes in all Vertebrates. Among invertebrates it exists 

 in Molluscs, especially in Cephalopods, in Arthropods,* 

 Worms (Reichert], and Echinoderms(Zfj'^). Yellow tissue 

 occurs in the ligamentum nuchae and the interlaminar verte- 

 bral ligaments, and is confined to vertebrates. Its fibres are at 

 first protoplasmic within, f and continue to grow by the in- 

 crease of the intercellular deposit on their outer surface. 

 White fibres do not increase in size when once formed. 

 The fibres may be the outgrowths of cells or (in tendons) 

 fibres and cells may be simultaneously formed. \ Fat is 

 sometimes laid down within the protoplasm of connective 

 corpuscles, especially in the parenchymatous form (Cza- 

 jewicz). 6th. Cartilage is a form of connective tissue in 

 which rounded or fusiform, rarely processed (larynx of ox) or 

 stellate (Nautilus, sharks), cells are contained in a ri^id chon- 

 drinous|| intercellular matrix. The simplest form parenchy- 

 matous cartilage is a mass of cells with little or no matrix ; 

 this is found in Geryonidae and Siphonophora, the gill sup- 

 ports of Chaetopods, Limulus,^[ Cephalopods, the notochord, 

 the skeletons of Myxinoid fishes, &c. Hyaline cartilage 

 has a glassy matrix often marked with clear rings round the 



* Schlossberger denies its presence in Crustacea, as the so-called fibrous 

 tissue in the crab's claw contains no gelatin. 



t Nitrate of silver produces a black marking within these fibres (Reckling- 

 hausen), and their centre takes a carmine dye (Frey). Rollett could not 

 detect a tubular structure in section, and Von H'ittich could not stain the 

 interior with indigo. 



J Krause regards the connective tissue corpuscle as connected with the 

 lymphatic system. He describes spindle-shaped elements (Inoblasts) as 

 components in tendons. 



Sometimes fat cells have no membrane, as in Amphibia. Flemming 

 describes fat as laid down in the tunica adventitia of blood vessels. 



|| Young cartilage often does not give the reaction of chondrin. 



f The cartilage in Limulus contains chitin in its intercellular substance 

 (Gegenbaur). 



