206 Scientific Proceedings, Royal Dublin Society. 



of hydrogen peroxide. In two eases only was a colour produced with 

 ffl-naphthol, and in these it was faint and indirect, but all reacted with 

 benzidine indirectly. However, it is certain that the latter coloration was 

 not always due to an oxydase, as it was also produced in boiled specimens. 



3. The presence of water-soluble phycophsein in small quantity during 

 life and its reduction to a colourless substance at death, is suggested as an 

 explanation of the much-discussed colour-change occurring in brown algss. 



I have much pleasure in thanking Professor H. H. Dixon for the criticism 

 and advice which he continually afforded me. I wish also to acknowledge my 

 indebtedness to Professor K. Tendo, of the University of Sapporo, for his 

 kindness in assisting me with the identification of the various algee. 



Bibliography. 



1. Atkins, W. E. G. — Oxydases and their Inhibitors in Plant Tissues. 



Pt. i. Sci. Proe. E. Dub. Soc, vol. xiv (N.S.), No. 7, Aug., 1913. 



2. loc. eit. Pt. ii. No. 8, Dec, 1913. 



3. Kylin, H. — tJber die Farbe der Florideen und Cyanophyceen. 

 Zeitschr. f. Bot. v, 5, p. 396. 1913. 



4. tJber die Farbstolfe der Fucoideen. Zeitschr. f. pliysiol. 



Oliemie, Ixxxii, p. 221. 1912. 



5. Zur Biochemie der Meeiesalgen. Zeitschr. f. physiol. Chemie, 



Ixxxiii, 3, p. 171. 1913. 



6. MoLiscH, H. — tJber den braunen Farbstoff der Pheeophyceen und 

 Diatomeeu. Bot. Zeit., Ixiii, 1, p. 131. 1905. 



7. Erwiderung auf die Kritik M. Tswett's iiber meine Arbeit. 



Vide supra. 



8. Sentek. — Zeitschr. f. physikal. Chem., li, p. 673. 1905. 



9. TsvifETT, M. — Zur Kenntniss der Plmophyceen-Ywh^io^e. Deut. Bot. 

 Gesellsch., xxiv, 1, p. 236. 1906. 



10. Kritischc Bemerkungen zu Molischs Arbeit uber die 



PAfeoiy*//6w;/-Farbstoffe. Bot. Zeit., xxiv, 2, p. 274. 1909. 



