CONNECTIVE TISSUES 



39 



not in the cells. They are composed of the following 

 parts : — 



I. Formed material. 

 («) Fibres. 

 (6) Matrix. 

 II, Spaces (Connective Tissue Spaces). 

 III. Cells. 



I. Formed Material. — (a) Fibres (fig. 10). — 1st. Non- 

 elastic (White Fibres). These are delicate, transparent fibrils 

 arranged in bundles. They do not branch, and the}^ have a 

 mucin-like matrix between them. They are composed of a 

 non-elastic substance, collagen. This is a sclero-protein 

 (Appendix), and it gives the biuret reaction but not the tests 



Fig. 10. — Bundles of White Fibres, with Fibroblasts (a) and Elastic Fibres 

 anastomosing with one another (6). 



for the proteins depending on the presence of the benzene 

 nucleus. It contains neither tryptophan nor tyrosin (p. 17), 

 but it is rich in amino-acetic acid — giycin. It is insoluble 

 in cold water, but swells up and becomes transparent in 

 acetic acid. It has a great affinity for carmine, and stains a 

 pink colour with it. When boiled, it takes up water to form 

 a hydrate, gelatin, a substance soluble in hot water, and 

 forming a jelly on cooling (see Chemical Physiology). 



2nd. Elastic Fibres. These are highly refractile elastic 

 fibres, which branch and anastomose with one another. 

 They are composed of Elastin, a sclero-protein which is very 

 poor in tyrosin, and hence gives the xantho-proteic test very 

 faintly. It is insoluble in both cold and hot water and is 

 not acted on by acetic acid. It stains 3'ellow with [picric 

 acid and it has no affinity for carmine. 



