CONNECTIVE TISSUE. 



53 



fibres are embedded as ledge-like thickenings 

 occur homogeneous 



\ 



If we search further, we meet with transitions to broader 

 and thicker ramified fibres (c), which, in contradistinction to 

 the extensible finer ones, gradually assume a considerable 

 inflexibility and brittleness. Their diameter may increase to 

 0.0056 to 0.0065 mm. 



In other places, the walls of the larger arteries, we find co- 

 herent elastic membranes, in which fine fibrillar and reticular 



There also 

 layers of elastic sub- 

 stances which are perforated with little holes 

 (Fig- 53) ! )- Between these and a small- 

 meshed reticulum of very broad, flat elastic 

 fibres (2) it is, indeed, often 

 impossible to make a demar- 

 cation. 



These changing elastic ele- 

 ments are met with in still 

 another condition. They 

 form a structureless sheath 

 around many connective-tis- 

 sue bundles. As surely as 

 an innumerable quantity of 

 these bundles are without 

 envelopes, and exhibit only 

 a fibrillated cord, even so 

 little can the presence of a 

 sheath around others be 

 doubted ; as on those which 

 pass from the arachnoid, at 

 the base of the brain, to the 

 larger blood-vessels, on the 

 fasciculi of the tendons, on 

 much of the subcutaneous cellular tissue, 

 agents which produce considerable swelling 

 strange appearance is caused (Fig. 54). The sheath is torn 

 into transverse portions, and these rapidly contract between 

 the protruding portions of the connective-tissue bundle to 



Fig. 53.— Elastic net- 

 work fi\,m the aorta ; I, 

 of the ox ; 2, of the 

 horse. 



Fig. 54. — Acon- 

 nective-:issue bun- 

 dle, from the base 

 of the humanbrain, 

 treated with acetic 

 acid. 



If we apply re- 

 as acetic acid, a 



