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XIX. 



AWARD OF THE BOYLE MEDAL 



TO PROFESSOR HENRY HORATIO DIXON, Sc.D., F.R.S., 



1916. » 



Report of the Science Committee. 



Professor Henry H. Dixon's earliest paper is a communication to the 

 Royal Dublin Society in 1892 on the " Walking of Arthropods," wherein he 

 investigates the manner in which various insects, spiders, &c, walk. The 

 paper displays ingenuity and resource in a remarkable degree. Having been 

 appointed to the post of Assistant to the Chair of Botany in the University 

 of Dublin in 1894, he definitely devoted himself to Botanical research ; at 

 first chiefly to plant anatomy and cytology. He published work on the 

 anatomy of orchids, describing the structure of a previously unknown type of 

 leaf, which shed light on the origin and development of cylindrical leaves 

 in that group. In cytology he worked out the fertilization of Pinus 

 sylvestris, and contributed some of the earliest observations on the reducing 

 division in plants ; he first described the strepsinema stage in this mitosis, 

 and gave an account of its origin. Subsequent work on genetics has 

 brought out the importance of the recognition of this stage in theories of 

 heredity. In this connexion may be mentioned his observations on the 

 nucleolus of cells, and his theory as to its function ; and also the work clone 

 in elucidation of the structure of coccoliths and coccospheres and of their 

 origin. 



In 1893, in collaboration with Dr. J. Joly, he published the Tension 

 Theory of the Ascent of Sap in Trees. In this work a problem of long 

 standing was attacked, and a rational explanation found as to how the sap 

 is raised in high trees. This theory, which has now been generally accepted, 

 led to a great deal of physiological and physical experiment of a high order, 

 carried out with a view to testing the applicability of the theory and its 

 ability to explain the phenomena of the rise of water in trees. Among the 

 researches carried out by Dixon in this connexion were investigations on 



1 The presentation was made at the Scientific Meeting of the Royal Dublin Society, 

 held on the 23rd January, 1917, when the Medal was handed to Professor Dixon by the 

 President, The Right Hon. Lord Rathdonnell, h.m.l. 



SCIENT. PEOC, K.D.S., VOL. XV., NO. XIX. 2 G 



