SOLID PARTS OF ANIMALS. 



As far as their chemical constitution is concerned, they may 

 be divided into two classes : One class, destined to oppose a great 

 resistance, becomes transparent when boiled, and is gradually 

 converted into gelatin. The ligaments belonging to the second 

 class are very elastic. This elasticity supplies the place of mus- 

 cular action, by enabling them, after being distended, to resume 

 their primitive size and shape. To this class belongs the liga- 

 ment of the neck, which supports the head of ruminating animals 

 and horses. The ligaments which draw back the claws in the 

 animals belonging to the genus felis, and also the yellow liga- 

 ments placed in man between the vertebrae, belong to the same 

 class. Anatomists were of opinion that these ligaments were of 

 the same nature as the fibrous membranes of the arteries ; and 

 this opinion has been confirmed by the experiments of Berzelius. 



He found that when the yellow intervertebral ligaments are 

 heated they undergo a sort of semifusion. They swell up, and 

 after complete combustion leave a small quantity of white ash, 

 consisting principally of phosphate of lime. When these liga- 

 ments are boiled for a long time in water, during twelve or six- 

 teen hours for example, they do not become in the least soft, nor 

 do they undergo any alteration ; yet the water extracts a small 

 quantity of gelatin, derived, doubtless, from the cellular substance 

 mixed with the ligament. The ligament itself is neither dissolv- 

 ed nor softened, though kept for weeks in contact with alcohol, 

 ether, or concentrated acetic acid. 



But it is dissolved slowly, without the application of heat, by 

 sulphuric, nitric, and muriatic acids. And the solutions, when 

 diluted with water, are not precipitated by potash or prussiate of 

 potash, but they are by the infusion of nut-galls. After having 

 been saturated by ammonia and evaporated to dryness, the muriatic 

 acid solution leaves a matter soluble both in water and in alco- 

 hol. The precipitate from the aqueous solution by infusion of 

 nut-galls is almost all soluble in boiling water and in alcohol. 



The solution in acids takes place much more rapidly when 

 they are diluted and gently heated. The substance behaves in 

 the same way with caustic potash. When this last solution is 

 heated it gives the smell of dissolved horn. Acetic acid throws 

 : down from it a very slight precipitate. The matter which re- 

 mains after the saturated potash solution is evaporated to dryness 

 is soluble both in alcohol and water, and exhibits the same cha- 



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