1. Penicillium glaucum. 2. Mucor mucedo. 3. Mucor piriformis (Fischer, possibly identical with 2). 4. Mucor stolonifer (Ehrenberg). 5. Botrytis cinerea (Pers). 6. Mucor racemosus (Fres). 7. Monilia fructigena (Pers). 8. Fusarium putrefaciens (Osterwalder). 9. Cephalothecium roseum. CHAPTER V. ACTION OF ENZYMES. “The living organism is enabled by the use of enzymes to bring about, under ordinary conditions of temperature and moderate concentrations of acid or alkali, many chemical reactions which would otherwise require a high temperature or powerful reagents.”--W. M. BAYLISS. In a recent work,[94] Dr. Bayliss defines enzymes as the “catalysts produced by living organisms.” A catalyst is a body which greatly accelerates the rate of reaction in chemical processes, without apparently taking part in the process. For instance, peroxide of hydrogen is decomposed into oxygen and water by mere contact with finely divided platinum, while the latter remains unaltered in the process. In this case the platinum black is the catalyst.[95] [94] “The Nature of Enzyme Action,” by Dr. W. M. Bayliss, FRS. [95] The important discoveries of MM. Paul Sabatier and Senderens on the catalytic action of finely divided metals, notably nickel and copper, have recently been extended to a study of the catalytic action of various metallic oxides. In the _Comptes rendus_, MM. Paul Sabatier and A. Mailhe give an account of a new synthetic method, based on the catalytic effect of titanium oxide, which would appear to possess many practical applications. They show that if a column of titanium dioxide is maintained at a temperature of 280°–300° C., and a mixture of the vapours of a primary alcohol and a fatty acid (other than formic acid) is led over it, the corresponding ester is formed. The same limit is here reached instantaneously as was found by Berthelot after prolonged contact. An excess of either constituent favours the limit of combination of the other. Following this method, the methyl, ethyl, propyl, butyl, isobutyl, and isoamyl esters of acetic, propionic, butyric, isobutyric, isovaleric and caproic acids have been prepared. Esters of benzyl alcohol have also been readily obtained by this method. The inverse action--the direct hydrolysis of esters by water--is also easily effected, and the use of titanium dioxide reduces any secondary reactions to a negligible amount. See Nature, March 9, 1911, p. 54. See also Dr. Sand’s paper--bibliography.