232 MANUAL OF HISTOLOGY. 



form from which collagen as well as chondrigen is produced : comp. what 

 has been already stated in regard to elastic cartilage ( 108). 



Analysis of organs wholly formed of connective-tissue has been 

 undertaken comparatively rarely up to the present. The proportion of 

 water in the tendons amounts according to Chevreul to 62 '03, in the 

 cornea to 73-94-77*82 per cent. (His). The latter has, therefore, 26*06- 

 22 '18 of solid matters, of which in one case 20*38 were converted into 

 glutin 011 boiling, and 2*84 was found to be made up of organic non- 

 glutinous substance. The latter may be referred to the corneal cells and 

 their processes, as well as the membrane of Descemet. Together with 

 these were found besides 0*95 per cent, of mineral constituents, of which 

 0*84 were soluble in water. 



REMARKS. 1. According to A. Schmidt "fibrinogen" is almost always one of the 

 components of such exudations. 2. We can thus isolate connective-tissue passages 

 with their terminal layers, and remains of cells in the interior, by means of sulphuric, 

 hydrochloric, or nitric acids. Prolonged boiling also in alcohol acidulated with 

 hydrochloric acid, and subsequent maceration in water, leaves the protoplasm of 

 the cells still remaining, while the interstitial substance undergoes solution, and the 

 elastic fibres crumble up. 



138. 



Connective-tissue forms a large part of the ordinary investing and sus- 

 tentacular substances of the body. It connects organs with one another, 

 envelopes them, and fills out interstices between them and between their 

 divisions : it fixes parts against one another, forms passages for vessels 

 and nerves, and cavities for collections of fat cells, &c. This so widely- 

 distributed tissue, then, comes under our consideration, as regards its 

 physical properties, mainly for the building up of our body. Loosely 

 interlaced as regards its fasciculi, connective-tissue presents itself in the 

 form of a yielding extensible substance. But, on the other hand, we usually 

 encounter a more dense and intimate interweaving of its fibres, especially 

 in formed connective-tissue; so that a greater or less degree of solidity is 

 attained, as opposed to the extensibility of that formless species. The 

 plentiful occurrence in it of elastic elements has also a great influence on 

 the physical qualities of the tissue. 



On the other hand, we encounter structures formed of connective-tissue 

 which play a part in the chemical processes of the system, owing to their 

 great vascularity or abundant exudatory activity, as, for instance, the 

 skin and mucous membranes. This depends, however, properly speaking, 

 upon the contained blood-vessels. 



It is usually supposed, though without sufficient data for proof, that 

 the transformative capacities of connective-tissue in regard to the matters 

 passing through it are in general but small. We are led to infer this by 

 the passive part which the tissue takes in the assimilative revolutions of 

 the body, or its slight inclination to decay, and by the poorness in vessels 

 of many parts formed of it. 



This interchange of matter, however, be it great or small, is still 

 completely veiled in obscurity as regards its nature. The fact that 

 glycin and leucin ( 35 and 31) are products of the artificial decomposi- 

 tion of glutin, while elastic material yields the last of these only, may 

 give us some slight point to hold by in the present helpless state in 

 which we find ourselves. 



Some years ago, from the connective-tissue theory of Bonders and 

 Virchow, an idea sprung up that the cellular networks of its cor- 



