AREOLAR, TISSUE. Ixxiii 



sheath (Kolliker) ; and it will be afterwards noticed as constituting a special 

 form or variety of connective tissue occurring elsewhere. 



The elastic fibres lie, for the most part, without order, among the bundles of white 

 filaments ; but here and there we see 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 (c). This remarkable disposition of the elastic 

 fibres, which was pointed out by Henle, is not uncommon 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 ; moreover, the whole 

 appearance is explained by some histologists 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 the operation of that 

 agent, is rent into shreds or segments, mostly annular or spiral, which cause the con- 

 strictions. Kolliker, who admits that some fasciculi have a sheath, yet supposes that 

 in these, as well as in naked bundles, the encircling fibres are produced by prolonga- 

 tions from the corpuscles (to be immediately noticed), uniting in form of a thread, or 

 of a network wrapped round the bundle. 



Bodies, mostly with nuclei, and of the nature of cells, although not 

 shown to possess a distinct cell- wall, are found in the areolar tissue. These 

 are the connective-tissue-corpuscles. Some lie in the meshes of the tissue, 

 others are included within the fasciculi. The former are of no very regular 

 shape, rounded or oval (as in fig. xxxiv.), or, as described in the frog by 

 Ktihue, having a stellate or jagged outline with processes or offsets of 

 unequal size and length, here and there connected with processes from 

 neighbouring corpuscles in short, misshapen little masses of protoplasm, 

 but containing usually a well-formed oval nucleus and conspicuous nucleolua. 

 Those within the fasciculi are fusiform, with pointed ends, and lie length- 

 wise in the direction of the fasciculus (as shown, though imperfectly, in 

 tig. xxxvi. c.). 



These bodies were imagined to be hollow, and it was conceived that, by the inter- 

 communication of their supposed tubular offsets they formed a system of reticulating 

 canals destined to distribute nutritive fluid to the connective tissue and other parts 

 into which that tissue enters. But, though soft, they are evidently solid objects ; and 

 though they probably effect some chemical change, or exert some other influence on 

 the interstitial nutritive plasma, or in some other way minister to nutrition, it is 

 clearly not as a system of channels for the conveyance of fluid. In the frog they 

 exhibit slow but distinct movements and changes of shape, like the pale blood-cor- 

 puscles ; and they may be regarded as cells retaining their primitive protoplasmic 

 condition, and subservient not only to the nutrition, but to the extension and repair 

 of tissues. There'can be little doubt, moreover, that they are largely concerned in 

 pathological and degenerative, as well as in reparative processes. 



The areolar tissue contains a considerable quantity of water, and conse- 

 quently loses much of its weight by drying. It is almost wholly resolved 

 into gelatine by boiling in water. Acetic acid causes ifc, that is, the bundles 

 of white fibrils, to swell up into a soft, transparent, jelly-like mass. 



Numerous blood-vessels are seen in the areolar tissue after a minute 

 injection. These for the most part only pass through it on their way to 

 other more vascular textures, but a few seem to end in capillaries destined 

 for the tissue itself, and dense clusters of vessels are distributed to the fat- 

 lobules. Large lymphatic vessels proceeding to distant parts also pass along 

 this texture, and abundant lymphatic networks may be discovered in many 

 parts of the subcutaneous, subserous, and subniucous areolar tissue, having 



