56 



CONNECTIVE TISSUE. 



Fis. 30. 



microscope the elastic fibres appear transparent and colonrless, with a 

 strong, well-defined, dark outline. They are further remarkable for 

 their tendency to curl up, especially at their broken ends, which gives 

 them a very peculiar aspect ; and in many parts of the areolar tissue 

 they divide into branches and join or anastomose with one another, 

 in the same manner as in the pure elastic tissue (a). They differ among 

 themselves very widely in size, some being as fine as the white fila- 

 ments, others many times larger. 



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

 white filaments ; but here and there we see what appears to be an elastic fibre 

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

 AVhen acetic acid is applied, the fasciculus swells out between the constricting 

 turns of the winding fibre, and iDresents a highly characteristic apjiearance (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 niay be alwaj's seen 

 in that which accompanies the arteries at the base of the brain. It must be 

 observed, however, that the encircling fibre sometimes fonns not a continuous 

 spiral, but several separate rings ; moreover, the whole aispearance 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 the operation of that agent, is rent into 

 shreds or segments, mostly annular or spiral, which cause the constrictions. Indeed, 

 some bundles have been shown to possess such a sheath, made uji of flattened 



cells (Ranvier, Key and Retzius). 

 Moreover, the union of branches of 

 the coi-jiuscles (to be immediately 

 noticed) around a bundle may, in 

 some instances, be the cause of the 

 appearo.nce (KoUiker). 



A very different view of the struc- 

 ture of areolar tissue from that 

 here stated was taken by Reichert, 

 and adopted by Virchow. Donders, 

 and other distinguished histologists. 

 According to this view the apparent 

 bundles consist of a substance in 

 reality amorjihous or homogeneous, 

 and its seeming fibrillation is partly 

 artificial, tlie result of cleavage, and 

 partly an optical illusion, arising 

 from creasing or folding. In point 

 of fact, however, the bundles readily 

 separate into fibrils after exposure 

 to dilute solutions of chromic acid, 

 or to lime-water, or to barji;a-water, 

 by which the uniting matter is dis- 

 solved ; so that there can be no 

 doubt of their truly fibrillar struc- 

 ture. At the same time it is not 

 denied that immature fasciculi may 

 l^robably occiir, in which the fibril- 

 lation is incomplete. 



NECTivE Tissue 



SUBCUTANFOUS CoN- 



YouNG Guinea-pig. 



Magnified 350 diameters. 



d, branched corpviscle ; e, flattened cor- 

 puscle ; [/, granular corpuscle ; /, fibrillateil 

 cell ; I, I, leucocytes or migratory cells. 



Ground-substance and 

 Corpuscles. — The fibrils are, 

 as before said, united into the 

 small bundles and laminae which are visible to the naked eye by 

 means of a variable amount of homogeneous cementing matter or 



