CHEMICAL BASIS OF THE ANIMAL BODY. 1201 



occurs when gelatin is taken into the stomach. From the con- 

 ditions under which the change is effected and from certain 

 evidence deducible from analysis there can be but little doubt 

 that the conversion takes place as the result of hydrolysis, as in 

 the case of the formation of true peptones from proteids. 



Recent researches have shewn that, the hydrolytic decomposi- 

 tion of gelatin by digestive enzymes gives rise to products analo- 

 gous to those obtainable by the same method from the proteids. 

 Thus during both its peptic and tryptic digestion certain primary 

 products are formed to which the name gelatoses or glutoses 

 may be applied and which have so far been distinguished as 

 proto- and deutero-gelatose. Accompanying these, in variable 

 amount, are other products known as gelatin-peptones. The 

 latter are to be regarded as a product of the further action of 

 the enzymes on the first formed gelatoses and, like the true 

 peptones in their relationship to the albumoses, may be sepa- 

 rated from them by their non-precipitability on saturation with 

 ammonium sulphate, a reagent which completely precipitates 

 the gelatoses. Protogelatose is partially precipitated by satu- 

 ration of its solution with common salt, and completely so on 

 the simultaneous addition of acetic acid. Deuterogelatose is 

 not precipitated by either of the above reagents. The so-called 

 true gelatin-peptones have not yet been obtained in sufficient 

 quantity to admit of their complete examination. The products 

 of the digestion of gelatin appear to give a distinct biuret reac- 

 tion with caustic soda and sulphate of copper, and like the pep- 

 tones (and albumoses) are not precipitated by taurocholic acid, 

 which precipitates gelatin from its solutions. 



Reticulin. This is the name given to the substance of which the 

 connective-tissiie fibrils of reticular or retiform tissue, as met with 

 in lymphatic glands or the mucous membrane of the intestine, are 

 composed. It resembles gelatin in several respects but requires 

 further investigation. 



Chondrin. 



The matrix of hyaline cartilage is composed of an elastic, 

 semitransparent substance which is insoluble in cold or hot 

 water and does not swell up appreciably by treatment with 

 either water or dilute acetic acid. By prolonged treatment 

 with water under pressure in a Papin's digester it is gradually 

 dissolved and yields a solution which gelatinizes on cooling and 

 now contains the substance usually spoken of as chondrin. The 

 hyaline matrix of cartilage appears thus to bear the same rela- 

 tionship to chondrin that the ground-substance of connective- 

 tissue (collagen) does to gelatin, and is therefore frequently 

 spoken of as 'chondrigen.' 



The substance known as chondrin, which is obtained in 



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