ARRANGEMENT OF FIBRES IN AREOLAR TISSUE. 



229 



striation, and also the tendency which the elastic fibres show to break across (seldom or never 

 splitting longitudinally), are indications of the original formation of the fibres as rows of 

 isolated particles, which subsequently become fused together. 



In areolar tissue the bundles of white fibres intercross in all directions 

 (fig. 262), and exhibit every degree of curvature. The bundles are very 

 variable in size, the number of filaments in a bundle presenting a corresponding 

 variation ; and the laxity or density of the tissue depends chiefly upon the size of the 

 bundles and the closeness with which they are packed. 



The elastic fibres of areolar tissue run in the ground-substance between the 

 white bundles, but when the latter are large and occupy almost the whole of the 

 tissue the elastic fibres often appear to lie upon the surfaces of the bundles, and we 

 even see here and there what appears to be an elastic fibre winding 

 round one of these bundles, and encircling it with several spiral 

 turns. When acetic acid is applied, the fasciculus swells out between 

 the constricting turns of the winding fibre, and presents a highly 

 characteristic appearance (fig. 263). This remarkable disposition of 

 the elastic fibres, which was pointed out by Henle, is not uncommon 



Fig. 263. BUNDLE OF WHITE FIBRES OF CONNECTIVE TISSUE SWOLLEN BY ACETIC ACID. (Toldt.) 

 From the subarachnoid tissue at the base of the brain. 



Fig. 264. PART OF A MODERATELY LARGE TENDON IN TRANSVERSE SECTION. (E. A. S.) 



a, areolar sheath of the tendon, with the fibres for the most part running transversely, but with two 

 or three longitudinal bundles, 6 ; I, lymphatic cleft in the sheath ; immediately over it a blood-vessel is 

 seen cut across and on the other side of the figure a small artery is shown cut longitudinally ; c, large 

 septum of areolar tissue ; d, smaller septum ; e, still smaller septum. The irregularly stellate bodies 

 are the tendon cells in section. 



in certain parts of the areolar tissue ; it may be always seen in that which 

 accompanies the arteries at the base of the brain. It must be observed, however, 

 that the encircling fibre sometimes forms not a continuous spiral, but several 

 separate rings. In such a case the appearance may be explained on the supposition 

 that the bundles in question are naturally invested with a delicate sheath, which, like 

 the elastic tissue, resists acetic acid, but, on the swelling up of the bundle under 



