SECT. 22.] CONNECTIVE TISSUES. 43 



Apart from this, the matrix of the different connective substances 

 agrees very much, being found, in different degrees, homogeneous, 

 finely granular, striated, or even made up of separable fibrillar and 

 in every degree of consistency, being mucous, gelatinous, firm, or 

 even of cartilaginous and bony hardness. 



In a chemical point of view, the variations of connective sub- 

 stance are just as great ; for although it is found in many cases 

 (bone, dentine and cement, true cartilage, and connective tissue 

 generally) to yield gelatine and chondrin, yet the gelatinous com- 

 position of the matrix: cannot by any means be acknowledged as 

 characteristic of, and essential to connective substances; such a 

 composition being wanting in many of them (connective substance 

 of invertebrate animals, mucous tissue, central masses of the in- 

 tervertebral cartilages, gelatinous tissue of fishes, homogeneous con- 

 nective tissues of vertebrate animals, in part, etc.). No accurate 

 chemical distinctive character of the matrix of connective sub- 

 stances can as yet be given ; for although we know that it contains 

 mucus, albumen, and colloid substances (in the intervertebral liga- 

 ments, Virchoic), chondrin, gelatin, and a body similar to the 

 substance of elastic tissue, yet not much is gained by this ; and, as 

 Reichcrt very properly remarks (Bindeg. p. 185), the task imposed 

 upon us consists rather in demonstrating the genetical connection 

 between these matters, and in showing that they are capable of 

 being converted into one another, as has been already stated, with 

 reference to the histological elements of connective substances. 

 Nevertheless, this much may be remarked, that just as cartilage, 

 bone, and fibrous connective tissue appear as the highest forms of 

 connective substances, so also, in a chemical point of view, gelatin 

 may be regarded as distinctive of a fully formed basal substance. 



The cells scattered in the matrix of the connective tissues are of 

 different kinds. By far the most interesting are those which may 

 be designated by the general expression cells of connective substance. 

 These cells, in fact, occur in all structures formed of connective 

 substance, and present a great uniformity in their several develop- 

 mental conditions, as well as in their physiological significance. 

 From the round shape which they possessed originally, and even 

 retain in mucous tissue and most cartilages, they pass into the 

 spindle or stellate form (cartilage cells of the cephalopoda, of certain 

 cartilaginous fishes, of enchondromatous tumours, connective-tissue- 

 corpuscles in the different forms of the connective tissue), and may 

 even become connected with each other, to form anastomosing 

 canals. Further, as long as they possess the round form, they 



