FIBROUS CONNECTIVE TISSUE. 61 



gelatin with albumin, a comparison which is of primary 

 importance in determining the exact genetic relationship of 

 these two bodies. 



In many investigations on the chemical nature and properties 

 of gelatin, the commercial product, purified perhaps by 

 precipitation with alcohol, etc., has been employed and with 

 valuable results, but in the light of present knowledge it 

 seems quite imperative to establish with definiteness the 

 chemical composition and reactions of gelatin from white 

 fibrous connective tissue, and for this purpose it is necessary 

 to have a product from a definite source and prepared in such 

 a manner as to insure freedom from admixture, however 

 slight, with any extraneous matters. The numerous proteid 

 reactions obtained with ordinary gelatin are, in many cases at 

 least, much less intense than those obtained with true proteids, 

 a fact which has frequently led to the suggestion that gelatin 

 owed its reactions in these cases to admixed albumin obtained 

 from the tissue cells, etc. 



When gelatin has once been prepared from the tissue- 

 collagen, its further purification becomes exceedingly difficult. 

 It is therefore of primary importance that the albumin, elastin 

 and mucin be completely removed from the collagenous tissue 

 prior to the conversion of the latter into gelatin. The removal 

 of these substances, however, from so compact a tissue as 

 tendon, with its predominance of collagenous fibers, is not 

 easy, and considerable time must be given in order to accom- 

 plish this with any degree of thoroughness. The agents 

 employed for the removal of these substances were water, 

 half-saturated lime-water, dilute acetic acid, and alkaline 

 pancreatic juice. 



PREPARATION A. 



Achilles tendons from oxen were carefully cleaned, freed 

 from fat, etc., and then cut into very small pieces. The finely 

 divided material (700 grams) was then soaked in thymolized 

 water, frequently changed, for several days, to remove as much 

 soluble matter as possible. It was next placed in 2 liters of 



