Award of the Boyle Medal to Professor Henry Horatio Dixon. 181 



Recently Dixon, in collaboration with Lieut. T. Gr. Mason and 

 Lieut. W. R. G. Atkins, has been making investigations on photo- 

 synthesis, and has succeeded in explaining the observation that a rise in 

 sucrose and not in hexoses is observed in green cells immediately after 

 illumination, when theory would demand that the formation of hexose 

 should be preliminary to the production of sucrose. The explanation, which 

 is founded on the localization of chemical reactions in special organs of the 

 cell, has been rendered very probable by preliminary experiments. 



In 1909 Dixon was invited to contribute to the international journal, 

 "Progressus Rei Botannicae," an account of his theory of the Ascent of 

 Sap. The resulting communication affords a standard account of the theory 

 and of the experimental evidence which has accumulated around it. This is, 

 however, surpassed in completeness by his recent volume appearing as one of 

 Messrs. Macmillan's Science Monographs, entitled " Transpiration and the 

 Ascent of Sap in Plants." This work is a model of exact scientific method 

 applied to the complex conditions prevailing in the plant. And when it is 

 remembered that the greater part of the book is a record of methods devised 

 by the author himself and, although in some places carried out in collaboration 

 with his pupils, yet always guided by his own scientific insight and learning, 

 it does not seem too much to hope that it will remain an enduring monument 

 of the author's principal work for Botanical Science. 



In accordance with precedent we may be permitted to add a word as 

 to that part of Dixon's work for Science which does not find record in his 

 publications. A pupil of the late Professor Edw. Percival Wright, and, in a 

 certain degree, also of the late Professor Strasburger of Bonn, Dixon has in 

 his management of the Botanic Gardens and of the Herbarium of the 

 University of Dublin worthily perpetuated the traditions of the Chair to which 

 he succeeded in 1904 upon the retirement of Dr. Wright. At the same time 

 it may be said that he first has introduced the experimental method of teach- 

 ing Botanical Science into the University of Dublin. Working with diligence 

 at every branch of his subject he has taught Botany as a fundamental branch 

 of Biology, and one which requires of the student who would master the 

 subject a training in the still more fundamental sciences which deal with the 

 inorganic. In Botanical Science the medical student finds the best introduc- 

 tion not only to Biology, but to the technique of the Microscope. This Dixon 

 has also recognized, and this has rendered his teaching of large classes of such 

 students educational in the highest degree. The many brilliant young men 

 who have gathered around him, and have worked with him, are a sufficient 

 testimony to the stimulating nature of his teaching. 



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