SECT. 26.] 



CONNECTIVE TISSUE. 



55 



I ig. 22. 



neetive tissue is less known; but it would seem, in many places, 

 to approach the clastic tissue in its composition. 



Connective tissue is, according to its nature, serviceable in the 

 animal frame, sometimes as a firm, unyielding substance, some- 

 times as affording a soft support to vessels, nerves, and glands, 

 and sometimes, finally, as a pliant material, filling up interstices, 

 and facilitating change of position. Wherever elastic elements 

 occur in it in large quantity, its purpose is altered ; and when it 

 contains a large number of fat-cells, or cartilage-cells, it attains a 

 softness or a resistance not occurring elsewhere. 



Connective tissue is invariably developed from 

 cells, — the fibrous form from fusiform or stel- 

 late vesicles, which unite to form long fibres or 

 networks, and, at the same time, break up 

 into fibrillae, frequently, even, before their coa- 

 lescence. The mode in which this happens is 

 not yet quite made out, still it is most proba- 

 ble that the cells, contemporaneously with their 

 elongation, pass, with their membranes and 

 contents, into a homogeneous, pulpy mass, 

 which then breaks up into a bundle of fine 

 fibrils and a small quantity of uniting sub- 

 stance. The homogeneous connective tissue 

 has, as yet, been but little followed in its de- 

 velopment ; but wherever it is collected in large 

 masses, it appears, in general, to arise like the 

 other, by the coalescence of round or elongated 

 cells, in which the metamorphosis has only gone Formative celIs of arcolar 

 the length of forming a homogeneous mass, but SSSTfiffl-K 

 not of fibrillation. On the other hand, certain ^ovtaSH "TcVn^SS 

 homogeneous membranes of connective tissue ^[ h ^^encto/ b rad\?' 

 are, perhaps, to be regarded as representing with distinct fibrils - 

 merely an intercellular substance. When the bundles of con- 

 nective tissue have once begun, they increase in length and 

 thickness, like the elastic fibres, till they have attained the size 

 which they possess in the adult ; and subsequently, also, there 

 arise in many places, new elements which become connected with 

 those already present. The perfect connective tissue is, when 

 un mixed, almost destitute of vessels, and as to nutrition, stands in 

 any case very low in the scale ; on which account, it is scarcely ever 

 the subject of diseased processes. It is different with the vascular 

 connective tissue ; but in this case the morbid changes do not 



