Introduction to Animal Morphology. 15 



connective tissue, cartilage, bone, cornea, dentine, &c., 

 characterized by having ovoid or branching cells in an 

 intercellular substance,* which may contain mucin, 

 collagen, chondrogen or ossein, all of which are mor- 

 phologically equivalent. In the embryo it appears as 

 a cluster of closely adpressed plastides with feeble cell- 

 walls, and is known as indifferent tissue, as its after 

 development into one or other of the series depends 

 on external influences. 



The forms of connective tissue are ist. Cellular or paren- 

 chymatous, consisting of rounded or fusiform cellsf with a 

 sparing intercellular substance, sometimes little more than a 

 thick cell-membrane. This simple form occurs in the ectoderm 

 of Coelenterata, gland parenchyma, the notochord, &c. 2nd. 

 Mucous tissue, masses of oval, spindle, or branched cells with 

 interlacing processes, with a copious intercellular substance 

 containing mucin. This exists in the discs of Jelly fishes, Tu- 

 nicates and Heteropoda, the gelatine of the umbilical cord of 

 Mammals, &c. 3rd. Retiform or areolar, fine anastomosing, 

 sparingly or non-nucleated fibres, swollen at their junctions, 

 often with amreboid cells in the interspaces. The connective 

 tissue of the vitreous humour of the eye, the investing reticulum 

 of absorbent glands,]: the tunica adventitia of blood vessels, 

 neuroglia, &c., are of this sort. 4th. Blood and lymph are 

 connective tissues with a fluid intercellular substance con- 

 taining cells (see p. 32). 5th. Fibrillar tissue, cells with 

 long or reticular processes in fasciculi together with fibres 

 and coiled fibrils around each fasciculus (Strieker). The inter- 



\Vhich can be demonstrated by darkening it with a weak Nitrate of 

 silver solution. It is altered protoplasm as shown in bone ( Waldcycr), car- 

 tilage (Remak and Furstenburg), connective tissue (Schultze and Bealc). 



t As this form includes lymph cells in its interstices, it is called cytoge- 

 nous (Kullikcr), or adenoid tissue (His). 



I Mitllcrs fluid is one of the best media. It 



consists of bichromate of potass 2$ parts, sulphate of soda, one part, and 

 distilled water, 100 parts. 



