52 ELASTIC TISSUE. 



similar to elastic tissue. This opinion is specially based on histo- 

 logical grounds, and rests, on the one hand, on the development of 

 elastic tissue and especially of nuclear fibres from the walls of cells, 

 and on the other hand, on the circumstance that certain membranes 

 and textural elements, which in their physical and chemical pro- 

 perties closely approximate to elastic tissue (as for instance, the 

 sheaths of the nerves), may be found to be formed from cell-mem- 

 branes. According to Bonders, the walls of all true cells, whether 

 occurring in the neurolemma, the capsule of the lens, &c., have the 

 following physical and chemical properties in common with one 

 another and with the elastic tissue obtained from them. The physi- 

 cal properties are their structureless, glossy character, their trans- 

 parency, elasticity, strong refractive power, and a specific gravity 

 higher than that of water. The chemical properties are their insolu- 

 bility in water, alcohol, and ether (all the physical properties remain- 

 ing unaffected by the application of these reagents) their insolu- 

 bility in acetic and other vegetable acids their difficult solubility 

 in dilute sulphuric, hydrochloric, and nitric acids their insolu- 

 bility in ammonia, and their slight solubility even in concentrated 

 solutions of soda and potash their swelling in acids and alkalies, 

 and their alkaline solutions gelatinising their difficult solubility in 

 boiling water, and the absence of gelatinisation in the solution. 

 The animal cellulose is rendered yellow by nitric acid, then after 

 the addition of ammonia, orange ; the colour is scarcely affected by 

 hydrochloric acid, or by a mixture of sugar and sulphuric acid ; it 

 is turned red on the application of Millon's test. Acetic acid 

 throws down from the alkaline solution a substance which is insolu- 

 ble in an excess of the reagent, and possesses the main characters of 

 animal cellulose ; it does not readily become decomposed, even in 

 morbid processes, if we except fatty degeneration. 



However important such generalizations of the facts in our pos- 

 session maybe for histology however such general views may throw 

 light on the further progress of this science, and may open out 

 future paths of inquiry, it would be by no means expedient, in the 

 present state of our knowledge, to regard all cell-membranes as 

 perfectly identical with the substance of elastic tissue ; for indepen- 

 dently of the circumstance that the above-mentioned properties are 

 not found in every cell-membrane and in every elastic membrane, 

 we know how differently reagents often act on cells and tissues, 

 according to their age or the state of their development. Further, 

 it can scarcely be questioned that the walls of very young cells, as 

 for instance, blood-corpuscles, pus-corpuscles, the deepest epi- 



