60 ANIMAL PHYSIOLOGY. [LESSON 21. 



351. Nerves, muscles, ligaments, tendons, are not gelatinous ; 

 this element forms no part of their structure, and consequently the 

 capillaries belonging to these tissues respectively, refuse to recognize 

 its presence, and pass it on. 



352. Albumen exists in a soluble state in animal fluids ; it may 

 be easily dissolved in water, when it forms a glairy, colorless, and 

 almost tasteless fluid. In this state, however, it is always found 

 combined with a minute quantity of free Soda ; hence it is supposed 

 that pure Albumen is insoluble in water, and requires the assistance of 

 an alkali. Whether in its soluble or insoluble state, albumen always 

 contains a small portion of sulphur, which blackens silver ; for this 

 reason a silver spoon is made black at the breakfast table, when eggs 

 are present, and to avoid this contingency many persons prefer to use 

 a bone, or ivory spoon, with eggs. 



353. Albumen shows no disposition to become organized, or to 

 form tissues ; but after its introduction into the body of a living 

 animal, it changes into another compound, having new and peculiar 

 properties, called Fibrine. 



354. According to the analysis of Dumas, the ultimate compo- 

 sition of Fibrine, and Albumen, shows that the former contains less 

 Carbon, and more Nitrogen, than the latter ; the chemical compo- 

 sition of these elements does not appear to be of much account, as 

 the transformation of Albumen into Fibrine is much more a vital 

 than a chemical process. 



355. Like Albumen, Fibrine may exist in a soluble, or in a co- 

 agulated state ; but it is only found soluble in living animal fluids, 

 as the Chyle, Lymph, and Blood. When withdrawn from the blood- 

 vessels, the Blood soon coagulates, as do also the Chyle and Lymph ; 

 this coagulation is due to a change in the condition of the Fibrine, 

 the particles of which have a tendency to aggregation in a definite 

 and peculiar manner. This process is called fibrillation, which 

 seems to be allied to crystallization. 



356. A single fact will suffice to show the close chemical relation 

 subsisting between Albumen and Fibrine, that from both of these (no 

 less than from many vegetable substances used for food) a similar 

 substance may be obtained by a simple process. 



357. If boiled Albumen be dissolved in a weak solution of caus- 

 tic alkali, and the liquid be neutralized by an acid, a precipitate falls 

 down in grayish white flocks ; this being collected and washed, is 

 gelatinous, of a grayish color, and semi-transparent ; and when dried, 

 it is yellowish, hard, easily pulverized, tasteless, insoluble in water 



