The Origin of Life 29 



volume when put into a solution of lower osmotic 

 pressure. This has led and is possibly still leading to 

 the statement that the process of growth by a living 

 cell has been imitated artificially. Only one feature has 

 been imitated, the increase in volume ; but the essential 

 feature of the process in the living cell, i. e., the forma- 

 tion of the specific constituents of the living cell from 

 non-specific products, has of course not been imitated. 

 4. The constant synthesis then of specific material 

 from simple compounds of a non-specific character is 

 the chief feature by which living matter differs from 

 non-living matter. With this character is correlated 

 another one; namely, when the mass of a cell reaches 

 a certain limit the cell divides. This is perhaps most 

 obvious in bacteria which on the proper nutritive me- 

 dium take up food, grow, and divide into two bacteria, 

 each of which takes up food, divides, and grows ad 

 infinitum, as long as the food lasts, provided the harm- 

 ful products of metabolism are removed. If it be 

 true that specific synthetic ferments exist in each cell 

 it follows that the cell must synthetize these also, 1 



1 This would lead to the idea that the enzymes in the cell also syn- 

 thetize molecules of their own kind, or that, in other words, the syn- 

 thetic processes in the cell are of the nature of autocatalysis. Loeb, 

 Der chemische Character des Befruchtungsvor gangs, Leipzig, 1908. Ro- 

 bertson, T. B., Arch. f. Entwicklngsmech., 1908, xxv., 581; xxvi., 108; 

 1913, xxxvii., 497; Am. Jour. Physiol., 1915, xxxvii., i; Robertson and 

 Wasteneys, H., Arch. f. Entwicklngsmech., 1913, xxxvii., 485. Ostwald, 

 Wo., Uber die zeitliclien Eigenschaften der Entwicklungsvorgange, Leipzig, 

 1908. 



