GLUTIN. 397 



permanent and fibrous cartilages which were previously regarded 

 as non-gelatigenous, may be converted by very prolonged boiling 

 into a gelatinising and gluing substance ; but at the same time he 

 ascertained that in many of its other properties, this substance did 

 not coincide with ordinary gelatin ; hence he named it cartilage- 

 gelatin^ or chondrin. 



Bone-gelatin or glutin is obtained from the following tissues, 

 by boiling them for a longer or shorter time with water ; from the 

 cartilages of bone (after ossification), from tendons, the skin, 

 calves' feet, hartshorn, isinglass, the scales of fish, and from the 

 permanent cartilages, when they become ossified by disease. The 

 conversion of these animal parts into glutin proceeds without any 

 development of gas or absorption of air; acids promote this meta- 

 morphosis, just as they facilitate many similar transformations in 

 organic chemistry, which can take place by mere boiling without 

 their cooperation, but yet are hastened by their presence, as, for 

 instance, in the case of starch. 



We shall revert to this subject when treating of the individual 

 tissues, and of their relation to gelatin. 



Origin. We have already referred to the production of gelatin 

 from the gelatigenous tissues ; a comparison of the analyses of 

 pure gelatin with those of the tissues yielding it, will (in a future 

 part of the work) show us that there is no chemical difference 

 between the two, or that at most they only differ by a few atoms 

 of water. Hence it appears that in the formation of gelatin, 

 the material of the tissues only undergoes a re-arrangement of its 

 atoms, or a metamerism, or at most that it only assimilates water, 

 just as occurs when starch, inulin, and lichenin are converted by 

 prolonged boiling into dextrin or glucose. 



We shall have occasion to refer in considerable detail to the 

 production of gelatigenous from albuminous matters, when we treat 

 of cell-formation and the history of development. 



U seSi From what has been already said, it follows that we are 

 unable at present to discuss the uses of gelatin in the animal 

 body. The consideration of the tissues from which we obtain 

 gelatin by boiling, pertains solely to histology, and the tissues 

 themselves have as yet hardly fallen within the scope of chemical 

 investigation. We learn from a very superficial consideration of 

 the animal body that the gelatigenous tissues belong for the most 

 part to the lower class of tissues, which are only of use through 

 their physical properties ; they frequently afford strong points of 

 attachment for muscles, and furnish strong investments for impor- 



