124 ORIGIN OF GELATINE. , 



rience reaches, do not possess the power of producing 

 compounds of proteine, by virtue of any influence, out 

 of substances which contain no proteine. Animals 

 which were fed exclusively with gelatine, the most high- 

 ly nitrogenized element of the food of carnivora, died 

 with the symptoms of starvation ; in short, the gelatin- 

 ous tissues are incapable of conversion into blood. 



But there is no doubt that these tissues are formed 

 from the constituents of the blood ; and we can hardly 

 avoid entertaining the supposition, that the fibrine of 

 venous blood, in becoming arterial fibrine, passes through 

 the first stage of conversion into gelatinous tissue. We 

 cannot, with much probability, ascribe to membranes 

 and tendons the power of forming themselves out of 

 matters brought by the blood ; for how could any matter 

 become a portion of cellular tissue, for example, by 

 virtue of a force which has as yet no organ ? An al- 

 ready existing cell may possess the power of reproduc- 

 ing or of multiplying itself, but in both cases the pres- 

 ence of a substance identical in composition with cellu- 

 lar tissue is essential. Such 'matters are formed in the 

 organism, and nothing can be better fitted for their pro- 

 duction than the substance of the cells and membranes 

 which exist in animal food, and become soluble in the 

 stomach during digestion, or which are taken by man in 

 a soluble form. 



19. In the following pages I offer to the reader an 

 attempt to develope analytically the principal metamor- 

 phoses which occur in the animal body ; and, to pre- 

 clude all misapprehension, I do this with a distinct pro- 



