226 WHITE FIBRES. 



extending, in form of longitudinal bands, underneath the raucous membrane of 

 the windpipe and its ramifications. 3. Entering, along with other textures, into the 

 formation of the coats of the blood-vessels, especially the arteries, and conferring 

 elasticity on these tubes. 



MICROSCOPIC STRUCTURE OF CONNECTIVE TISSUE. 



The three kinds of connective tissue, the obvious characters and arrangement of 

 which have just been described, agree closely with one another in elementary 

 structure. They are all composed of a matrix or ground-substance, in which cells 

 are imbedded, and in this ground-substance and between the cells are fibres of two 

 kinds, the white and elastic. It is the different arrangement of the cells and fibres, 

 as well as the relative proportion of one kind of fibre to the other, that determines 

 the different characters of the varieties of connective tissue above enumerated. 



Ground-substance of connective tissue. The ground-substance, matrix, or 

 intercellular substance of the connective tissue is composed of a soft homogeneous 

 material which occupies the tissue between the cells and cell-groups, and in which, 



as above stated, the fibrous elements of 

 the tissue are found, it may be in so 

 great a quantity as altogether to obscure 

 the ground-substance in which they lie. 

 It serves thus to unite the fibres, at 

 least the white fibres, into the bundles 

 which they form, penetrating between 

 the individual fibrils of a bundle, and 

 enveloping the latter with a homo- 

 geneous sheath often of great tenuity. 



The ground-substance of connective 

 Fig. 258. CELL-SPACES OF SUBCUTANEOUS CONNECTIVE tissue appears to contain mucin. It IS 



TISSUE, THE GROUND SUBSTANCE HAVING BEEN . . , r ^ T i -11111. 



STAINED DEEPLY BY NITRATE OF SILVER, precipitated and rendered cloudy by 

 (E. A. S. ) 340 DIAMETERS. acetic acid. It becomes stained brown 



when treated with nitrate of silver and 



afterwards exposed to the light, in this respect resembling the intercellular substance 

 of an epithelium. The cells of the tissue lie imbedded in it, either in shallow pits 

 on the surface, or in spaces cell-spaces entirely enclosed by the ground-substance, 

 the spaces being for the most part rather larger than the contained cells, with 

 which, however, they correspond on the whole in shape. These cell-spaces (Saft- 

 Tcanalchen of Recklinghausen, lymphatic canaliculi of Klein and Burdon-Sanderson) 

 are brought into view when the tissue is stained with nitrate of silver, for they then 

 look white upon the brown ground (fig. 258). 



White Fibres. When examined under the microscope both the areolar and 

 fibrous tissues appear to be principally made up of exceedingly fine, transparent, and 

 homogeneous filaments, from about 50 ^ 00 to . 2 - B ^ 00 th of an inch in thickness, or 

 even less (fig. 259). These are seldom single, being mostly united by means of a 

 small and usually imperceptible quantity of the ground-substance into bundles and 

 filamentous laminae of various sizes, which to the naked eye appear as simple threads 

 and films. Though the bundles may intersect in every direction, the filaments of 

 the same bundle run nearly parallel to each other, and no one filament is ever seen 

 to divide into branches or to unite with another. The associated filaments take an 

 alternate bending or waving course as they proceed along the bundle, but still 

 maintain their general parallelism. This wavy aspect, which is very characteristic 

 of these filaments, disappears on stretching the bundle, but returns again when it is 

 relaxed. 



