TRANSACTIONS OF SECTION K. 839 



Other oxydases have been isolated from beets, dahlia, potato-tubers, and several 

 other plants. 



These discoveries led Bourquelot and Bertrand in 1895 to the explanation of a 

 phenomenon long known to botanists, and partly explained by Schiinbein as far 

 back as 1868. If certain Fungi (e.g.. Boletus luridiis) are broken or bruised, the 

 yellow or white flesh at once turns blue : the action is now traced to the presence 

 in the cell-sap of an oxydase, the existence of which had been suspected but not 

 proved, and the observers named assert that many fungi (69 out 107 species 

 •examined) contain such oxydases. 



It will be interesting to see how far future investigations support or refute the 

 suggestion that many of the colour-changes in diseased tissues of plants attacked 

 foy fungi are due to the action of such oxydases. 



Wortmann, in 1882, showed that bacteria, which are capable of secreting 

 diastase, can be made to desist from secreting this enzyme if a sufficient supply of 

 sugar be given them, and since then several instances have been discovered where 

 fungi and bacteria show changes in their enzyme actions according to the nature of 

 their food supply. Nor is this confined to fungi. Brown and Morris, in 1892, 

 gave evidence for the same in the seedlings of grasses : as the sugar increased, the 

 production of diastase diminished. 



It is the diastatic activity of Asperf/illus which is utilised in the making of 

 sake from rice in Japan, and in the preparation of soy from the soja bean in the 

 same country, and a patented process for obtaining diastase by this means exists ; 

 and Katz has recently tested the diastatic activity of this fungus, of Penidllium, 

 and of Bacterium meyatherium in the presence of large and small quantities of 

 sugar. All three organisms are able to produce not only diastase, but also other 

 enzymes, and the author named has shown that as the sugar accumulates the 

 diastase formed diminishes, whereas the accumulation of other carbohydrates 

 produces no such effect. 



Hartig's beautiful work on the destruction of timber by fungi obtains new 

 interest from Bourquelot's discovery of an emulsion-like enzyme in many such wood- 

 destroying forms. This enzyme splits the Glucosides, Amygdalin, Salicin, Coniferin, 

 &c., into sugars and other bodies, and the hyphoe feed on the carbo-hydrates. I 

 purpose to recur to this subject in a communication to this Section. The 

 fact that Asperyilhis can form invertins of the siicrase, maltase, and trehalase 

 types, as well as emulsin, inulase, diastase, or trypsin, according to circumstances 

 of nutrition, will explain why this fungus can grow on almost any organic 

 substratum it alights on, and other examples of the same kind are now coming 

 to hand. 



The secretion of special enzymes by fungi has a peculiar interest just now, for 

 recent investigations promise to bring us much nearer to an understanding of the 

 phenomena of parasitism than we could hope to attain a few years ago. 



De Bary long ago pointed out that when the infecting germinal tube of a 

 fungus enters a plant-cell, two phenomena must be taken into account, the 

 penetration of the cell-walls and tissues, and the attraction which causes the tips 

 of the growing hypha to face and penetrate these obstacles, instead of gliding over 

 them in the lines of apparent least resistance. 



The further development of these two themes has been steady and unobtrusive, 

 and from various quite unexpected directions more light has been obtained, so that 

 we are now in a position to see pretty clearly what are the principal factors involved 

 in the successful attack of a parasitic plant on its victim or ' host.' That fungi 

 can excrete cellulose-dissolving enzymes is now well known, and that they can. 

 produce enzymes which destroy lignin must be inferred from the solution of wood- 

 cells and other lignified elements by tree-destroying fungi. Zopf has collected 

 several examples of fungi which consume fats, and further cases are cited by 

 Schmidt, by Ritthausen, and Baumann. In these cases also there can be no doubt 

 that an enzyme or similar body is concerned. 



There is one connection in wiiich recent observations on enzymes in the plant- 

 cell promise to be of importance in explaining the remarkable destructive action 

 of certain rays of the solar-light on bacteria. As you are aware, the English 



