84 GENERAL ANATOJIY OF THE TISSUES. 



tion disappears, so that quite homogeneous fibres or fibrous reticulations 

 are produced. These may then either remain through life as fine elastic 

 fibres and networks, or by increasing in thickness they may pass into 

 the coarser form of the tissue. The more homogeneous elastic mem- 

 branes are nothing but close elastic networks, whose fibres have so much 

 increased in diameter, that only narrow spaces remain between them. 

 The perfect elastic tissue appears to undergo very little change of sub- 

 stance — at least it is, so to speak, non-vascular, even when it occurs in 

 large masses ; on the other hand, in those forms which still present in- 

 dications of the original cells, a certain movement of the juices may 

 still take place. Elastic tissue is not known to be regenerated, but new 

 formations of it are not rare. 



The elastic tissue is rarely found in large masses ; but it is very fre- 

 quently mixed with connective tissue, either in the form of isolated 

 fibres or of networks of various kinds. As true elastic organs we may 

 mention : — 



a. The elastic ligaments, in which the tissue, with only a slight ad- 

 mixture of connective tissue and hardly any vessels and nerves, exists, 

 so to speak, in a pure form. As such we have the ligamenta suhflava of 

 the vertebrae, the ligamentum nucha', certain ligaments of the larynx, 

 the stylo-hyoid ligament, and the ligamentum suspensorium penis. 



h. The elastic membranes, which appear in the form either of fibrous 

 networks or of fenestrated membranes, and are found in the walls of 

 the vessels, especially in those of the arteries, in the trachea and hron- 

 chice, and in i\iQ fascia superficialis. 



In all the vertebrate classes the elastic tissue is found in the same 

 localities as in man, and in a few particular situations besides, as in the 

 ligaments of the cat's claw, in the alary membrane of mammals, in the 

 folds of the alary membrane and in the lung sacs of birds. In the In- 

 vertebrata this tissue appears to be rare, and it is not even certain that 

 the elastic ligaments which occur in them (as, for example, in bivalves), 

 agree anatomically and chemically with the elastic tissues of the higher 

 animals. 



Of the different parts belonging to the elastic tissues, the so-called 

 nucleus-fibres of Gerber are almost alone those whose development has 

 been examined. With regard to these, Henle's view,* that they arise 

 by the coalescence of elongated nuclei, was almost universally received, 

 until lately Virchow and Donders nearly contemporaneously brought 

 forward another conception. Both these authors proceed from the in- 

 vestigation of the connective tissue, and show that what in it have been 

 held to be elongated, isolated, or more or less coalesced nuclei, are 

 nothing more than fusiform or stellate cells, with fine processes, which 



* [See article " Kernfasern," MuUer's Arcliiv. 1838.— DaC.J 



