No. 49S] 



PHYSIOLOGY 



in- 



undergone by matter in the process of living, its building 

 up and its breaking down, its anabolism and its katab- 

 olism. The intricacies of metabolism can scarcely be 

 conceived by one not familiar with the attempts to follow 

 them, and the biochemists deserve much credit for the 

 ingenuity of their methods. They have been most suc- 

 cessful in determining and isolating the multitudinous 

 katabolic products of vital activity, both the intermediate 

 and the final products, and in discovering clues to the 

 individual steps in the katabolic process. They have 

 even succeeded in making synthetically many of these 

 vital products, an achievement which was inaugurated by 

 Wohler in 1828 in the manufacture of urea. The labora- 

 tory synthesis of vital products has become, indeed, 

 almost a daily occurrence and has hence lost its former 

 miraculous appearance. It is not, however, certain that 

 the laboratory methods and the physiological methods 

 employed in such synthesis are identical. The steps of 

 the anabolic process are still obscure, and until they are 

 better known we can hardly look forward with confident 

 satisfaction to the artificial manufacture of living sub- 

 stance. Yet physiological alchemists do exist, and the 

 successful making of "life" has been heralded more than 

 once to a sensation-loving world. Such an achievement 

 is for the present only an idle dream, serving to gently 

 and pleasurably titillate the cerebral cells of the 

 dreamers. 



Of recent years physiological physics and physiological 

 chemistry have come to meet on common ground within 

 the realm of the new science of physical chemistry. It 

 has come to be clearly recognized that living substance 

 consists of organic colloidal, or jelly-like, material, per- 

 meated by inorganic matter. The colloidal matter seems 

 to consist of enormous complex molecules and aggregates 

 of molecules; the inorganic matter partly of small, 

 simpler molecules, and partly of ions, which are atoms or 

 groups of atoms charged electrically. As the life process 

 goes on, the living substance being now in a state of 



