PROBLEMS OF PHYSIOLOGICAL CHEMISTRY. 519 



must confess we have no answer, save in exceptional cases. Wher- 

 ever matter is found definitely arranged, it is also accompanied by 

 effects dependent upon the arrangement ; platinum, zinc, and sulphuric 

 acid, when connected in a proper manner, form a galvanic element 

 and give rise to a galvanic current. Similar relations exist in the ani- 

 mal body ; here we also find the constituents in a definite arrangement 

 which we term organization, and by means of which the body has con- 

 trol over such peculiar conditions that we can not, or at best only in 

 rare cases, imitate them in the laboratory, and produce the same reac- 

 tions as are produced by the body. Although we have been taught, by 

 the celebrated discovery of the artificial production of urea by Wohler, 

 that the compounds occurring in the organism may also be produced out 

 of the body, this and similar experiments have given no explanation of 

 the manner in which the reaction takes place in the organism. Neither 

 have those experiments been explained in which, after the introduction 

 of certain substances into the body, new compounds, not ordinarily 

 present, are found in the excretions. These investigations have, how- 

 ever, considerably increased our knowledge, by showing beyond a 

 doubt that intermediate products are formed in the body, which are 

 generally directly decomposed, and therefore withdrawn from obser- 

 vation, but which can be fixed by the introduction of foreign material, 

 and so protected from further decomposition. How they are produced 

 or fixed is not explained by these experiments ; even if we assume, for 

 instance, that the two components unite, with the elimination of the 

 elements of water, we have not the slightest idea how it is effected. 

 Numerous experiments, in which the amount of substances taken up 

 and excreted by the organism were determined, have given valuable 

 results, but not in regard to the reactions taking place in the body. 

 The chemistry of the living body shows the peculiarity that all reac- 

 tions take place at the temperature of the body, which is quite low, 

 without the intervention of strong reagents in the ordinary sense. If 

 we wish to produce similar reactions outside of the organism, we 

 generally employ a high temperature and substances which would 

 destroy the organism itself. For instance, to prepare hippuric acid 

 from benzoic acid and glycocol, in the laboratory, it is necessary to 

 heat both for some time to 160, while in the body it is only necessary 

 to dissolve them in blood, and pass the solution through a kidney, 

 when a combination is effected. A problem is here presented, the 

 solution of which is of the greatest importance to physiological chem- 

 istry, and which must, therefore, be attempted with all perseverance. 

 It is no longer sufficient to show that certain substances are changed 

 in the animal body, and give rise to the formation of others, nor does 

 it suffice to make the synthesis which the cell produces, by any means 

 whatever, but we must endeavor to work under similar conditions and 

 with the same means as the body itself. We must make our experi- 

 ments at the temperature of the body, we must employ no reagents 



