AREOLAR TISSUE. 



Ixxi 



others the filamentous structure predominates, or even prevails exclusively ; 

 but it does not seem necessary to designate these varieties by particular 

 names, as is sometimes done. 



When examined under the microscope, the areolar tissue is seen to be 

 principally made up of exceedingly fine, transparent, and apparently homo- 

 geneous filaments, from about 3"^^th to -2^00*- ^ an i Qcn i Q thickness, 

 or even less (fig. xxxv.). These are seldom single, being mostly united by 

 means of a small and usually imperceptible quantity of a homogeneous con- 

 necting 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 alter- 

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

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

 teristic of these filaments, disappears on stretching the bundle, but returns 

 again when it is relaxed. 



The filaments just described, though transparent when seen with trans- 

 mitted light under the microscope, have a white colour when collected in 

 considerable quantity and seen with reflected light ; and they not only occur 

 in the areolar tissue strictly so called, but form the chief part of the tendons, 

 ligaments, and other white fibrous connective tissues. They were long sup- 

 posed to be the only fibrous constituent existing in the areolar tissue, but it 

 has been shown (chiefly through the inquiries of Eulenberg, Henle, and 

 Bowman) that fibres of 



Fig. XXXV. 



another kind are inter- 

 mixed with them ; these 

 agree in all characters 

 and are obviously iden- 

 tical with the fibres of 

 the yellow elastic tis- 

 sue, and have accord- 

 ingly been named the 

 yellow or elastic fibres, 

 to distinguish them from 

 the white or waved 

 filaments above descri- 

 bed. They were at 

 one time termed nuclear 

 fibres (Kernfasern), on 

 account of their sup- 

 posed origin from nu- 

 clei ; but as it now ap- 

 pears that they have 

 no connection either 

 with nuclei or cells, 

 the latter appellation 

 must be abandoned. 

 Moreover, they differ 

 in chemical nature from 



cells and nuclei, in as much as they resist the action of boiling alkaline 

 solutions of potash and soda, of moderate strength, which very speedily 

 destroy the cells and nuclei. 



Fig. XXXV. FILAMENTS OP AREOLAR TISSUE, IN LARGER 



AND SMALLER BUNDLES, AS SEEN UNDER A MAGNIFYING 

 POWER OP 400 DIAMETERS. 



Two or three corpuscles are represented among them. 



