444 MOVEMENTS. 



in some of the ligaments of the larynx, the stylo-hyoid liga- 

 ment, and the suspensory ligament of the penis. The form 

 and arrangement of these fibres may be very beautifully 

 demonstrated by tearing off a portion of the ligamentum 

 nuchse and lacerating it with needles in a drop of acetic 

 acid. The action of the acetic acid renders the accessory 

 structures of the ligament transparent, and the elastic fibres 

 become very distinct. The same may be accomplished by 

 boiling the tissue for a short time in caustic soda. 



The third variety of elastic tissue can hardly be said to 

 consist of fibres, their branches are so short and their anas- 

 tomoses so frequent. This kind of structure is found form- 

 ing the middle coat of the large arteries, and has already 

 been described in connection with the vascular system. 1 

 The fibres are very large, flat, with numerous short 

 branches, " which unite again with the trunk from which 

 they originate or with adjacent fibres. In certain situ- 

 ations, the interstices are considerable, in proportion to the 

 diameter of the fibres, and the anastomosing branches are 

 given off at acute angles, so that they follow pretty closely 

 the direction of the trunks, and the anastomoses do not dis- 

 turb the longitudinal direction and parallelism of the fibres. 

 Indeed, the anastomoses are so numerous, and the intervals 

 so small, proportionally to the fibres, that we would believe 

 we had under observation a reticulated membrane, present- 

 ing openings, rounded and oval, some large and others 

 small." 2 These anastomosing fibres, forming the so-called 

 fenestrated membranes, are arranged in layers, and the struc- 

 ture is sometimes called the lamellar elastic tissue. 



The great resistance which the elastic tissue presents to 

 chemical action serves to distinguish it from nearly every 

 other structure in the body. "We have already seen that it 



1 See vol. i., Circulation, p. 244. 



2 The above description, taken from Henle's general anatomy, conveys a 

 very clear idea of the arrangement of the large elastic fibres in the " fenestrated 

 membranes" (HENLE, Traite d'anaiomie generate, Paris, 1843, tome i., p. 431). 



