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The British Association at Dundee. 
processes involved in pigment-formation.” “ Glucosides hydro¬ 
lysed by emulsin yield chromogens, which, acted on by oxydases, 
give rise to anthocyan pigments.” Miss Wheldale showed in 1909 
that the chromogen and the oxydase were, in certain cases at least, 
inherited separately, and that their isolation or concurrence cor¬ 
responded with the production of white and coloured flowers 
respectively. It is difficult to over-estimate the importance of this 
first demonstration of the actual material nature of the factors 
already recognised by Mendelian breeders. 
Chodat and Bach put forward the hypothesis that “ the com¬ 
plete oxydase consists of two parts—a peroxydase and an organic 
peroxide. An oxydase reacts with oxidisable reagents, such as 
guaiacum to produce a characteristically coloured product. Hence 
these reagents may he termed oxydase-reagents. Peroxydases 
react with oxydase reagents only if there be added, as a substitute 
for the organic peroxide of the complete oxydase, a source of active 
oxygen in the form of hydrogen peroxide. Both oxydases and 
peroxydases occur in the cells of plants, and may be identified in 
extracts therefrom.” 
The difficulty of using the results of the work of Chodat and 
Bach in carrying further the analysis of the Mendelian factors for 
flower colour on biochemical lines “ lay in the unsatisfactory nature 
of the methods of identifying oxydases derived from plant-tissues.” 
Keeble and Armstrong, by the use of a-napthol and benzidine, have 
now “ been able to map out the distribution of oxydase and per¬ 
oxydase in the flowers and other parts of various plants,” and 
though “ the technique is as yet imperfect,” the results afford 
“ strong confirmation, of the current hypothesis of the mode 
of formation of anthocyan pigments. This confirmation, how¬ 
ever, was rendered possible only by the fact ” that they worked 
“ with races of plants bred on Mendelian lines, and hence of known 
genetic constitution.” 
Space does not permit us to follow Dr. Keeble any further 
into the details of this work, which is, indeed, considering the com¬ 
plexity of the phenomena to be investigated, only just begun. Nor 
can we do more than barely mention his concluding suggestion 
(based on the discovery that “ after one or two days exposure to 
darkness, plants of Primula sinensis contain more peroxydase than 
sister-plants kept under normal conditions of illumination”) to the 
effect that the numerous diurnal rhythms observed in plants may 
act through periodic fluctuation in the amount of oxydase present. 
But the methods employed are certainly taking us a step further 
into an understanding of the actual causes at work in determining 
the evolution of new races of plants, and, as is always the case 
when a union between hitherto distinct lines of investigation is 
successfully established, our knowledge is advancing, and is likely to 
advance in the immediate future, by leaps and bounds. We most 
heartily congratulate Dr. Keeble on a most stimulating and 
fascinating address, excellent alike in matter and manner. 
The programme of papers was a full one. Portions of two 
mornings were devoted to joint meetings with other Sections, one 
with Section B (Chemistry), at which papers dealing with the bio¬ 
chemistry of flower pigmentation were read: the other with Section 
D (Zoology) was given to a discussion on “ The Origin of Life.” 
