290 T. Brailsford Robertson: 



products of the reaction is the catalysing agent have beeil 

 studied by the undermentioned investigators.^) 



The transformation of oxyvalerianic acid into the cor- 

 responding lactone affords an example of an autocatalytic re- 

 action in which the catalysing agent is used up during the 

 progress of the reaction,'^) instead of, as in the instances con- 

 sidered above, increasing in amount as the reaction progresses. 

 Of course any of the above reactions, taking place in the re- 

 verse direction, would also be of this type, as, for example, 

 the synthesis of methyl acetate from methyl alcohol and acetic 

 acid. The acceleration of the hydrolysis of Salicin by Emulsin 

 would also appear to afford an instance of this type of re- 

 action.^) 



As regards the occurrence of autocatalysed reactions among 

 the chemical processes accompanying lif e-phenpmena , it has 

 been pointed out by Loeb*) that the synthesis of nuclein, 

 which is the main chemical change following and accompanying 

 the process of cell-division, is an autocatalytic reaction in which 

 one of the products of the reaction, the nucleus or one of its 

 constituents, also accelerates the reaction. I have pointed out 

 that the process of cell-growth is also, in all probability, de- 

 pendent upon a reaction of this type and that its progress 

 can be very accurately represented by formulas similar to that 

 given above: ^) From the preceding considerations it is evi- 

 dent that, qualitatively speaking, the main characteristic of 

 autocatalysed chemical reactions in which one of the products 



1) W. Hentschel, Ber. d. Deutsch, ehem. Ges. 23, 2394, 1890. — 

 W. Müller, Zeitschr, f. physikal. Chem. 41, 483, 1902. — P. Henry. 

 Zeitschr. f. physikal. Chem. 10, 96, 1892. Ber. d. Deutsch, chem. Ges. 24, 

 1236, 1891. — ü. CoUan, ibid. 10, 130, 1892. 



2) P. Henry, 1. c. 



3) A. A. Noyes und Hall, Zeitschr. f. physikal. Chem. 18, 240, 

 1895. — G. Tammann, Zeitschr. f. physiol. Chem. 16, 285, 1892; 18, 

 428, 1895. 



*) J. Loeb, Diese Zeitschr. 2, 34, 1906. — Address delivered 

 at the seventh International Zoological Congress Boston Aug. 22, 1907. — 

 Univ. of California Publ. Physiol. 3, 61, 1907. — Vorträge und Aufsätze 

 über Entwicklungsmechanik. Heft 2: „Über den chemischen Charakter 

 des Befruchtungsvorganges und seine Bedeutung für die Theorie der 

 Lebenserscheinungen''. Leipzig 1907. 



**) T. Brailsford Robertson, Arch. f. Entwicklungsmechanik. 



