SIMPLE FIBEE. 



113 



be formed at first exclusively of simple fibres. These, however, 

 subsequently disappear, as its development proceeds. 



There is reason to believe that simple fibres constitute the matrix 

 in which the tissues generally are developed during embryonic life, 

 as well as the nidus in which repair takes place after solutions of 

 continuity with or without loss of substance (p. 91). 



Uses. Simple fibre is, therefore, not a permanent constituent of 

 the human body. It must be regarded as a merely temporary 

 element, laid down as a framework on which higher histological 

 elements may be developed, and which then becomes absorbed and 

 disappears. 



In this way, however, its relations to the tissues are all-important. 

 Since, also, coagulated fibrine consists of a network of similar fibres, 

 they become the medium for the spontaneous arrest of hemorrhage, 

 as before explained (p. 9 1). 1 



In pathological epigeneses four kinds of fibres are found : 1. 

 Cleavage fibres, by far the most common of all, which occur in in- 

 flammatory exudations after coagula- 

 tion ; 2. Fibres of coagulation, i.e. formed 

 by fibrillation of fibrine, as occurs in 

 colloid; 3. Cell-fibres, those formed in 

 cells (Fig. 50); 4. Nuclear fibres, those 

 formed of elongated nuclei (Figs. 51 

 and 174). 



The first two forms seem identical 

 with simple fibres. Nuclear fibres are 

 the embryonic form of the yellow 

 fibrous tissue. 



Fig. 50. 



Fibre-cells passing into fibres. 



Fig. 51. 



Fig. 52. 



Nuclear fibres. 



Simple fibres and nuclei in false membrane. 



1 The elastic spiral fibre in the trachese of insects is probably mere simple fibre ; 

 and the fibre found in the air-vessels of plants presents a similar appearance, 

 though of different chemical composition. 



8 



