396 SECTIONAL TRANSACTIONS.— K." 



The excess of the photosynthesised formaldehyde beyond that used in these 

 reactions undergoes polymerisation to hexoses, and these in their turn give 

 sucrose, starches, and celluloses. All the complex compounds are the natural 

 and inevitable results of the photosynthesis of formaldehyde in the presence 

 of small quantities of potassium nitrite. 



(c) Mr. G. E. Briggs. — The Efficiency of the Photosynthetic 

 Mechanism of Green Plants for Different Wave-lengths of 

 Incident Radiation. 



The desideratum is to know what fraction of the radiant energy absorbed 

 by the photosynthetic pigment or pigments is utilised in the conversion of 

 carbon dioxide into the primary product of photosynthesis, and the relation 

 between this fraction and the wave-length of the incident radiation. 



The problem resolves itself into deciding, firstly, which of the pigments plays 

 a direct part in the photosynthetic process; secondly, what portion of the 

 radiant energy absorbed by the photosynthetic organ is absorbed by the par- 

 ticular pigment or pigments ; and, finally, what portion of the incident energy 

 is used for the conversion of the carbon dioxide. 



{d) Prof. I. M. Heilbron and Dr. 0. Hollins. — Some Specu- 

 lations on the PJiyto-synthesis of Plant Products. 



As hexose sugars have been proved to be the sole products of the photo- 

 synthesis of the nitrogen-free compounds in the green leaf, the formation of 

 the innumerable other substances commonly met with in the plant must neces- 

 sarily be produced at some later stage, which is probably closely connected with 

 respiratory action. 



An examination of the constitution of plant compounds immediately brings to 

 light the fact that the predominant carbon nuclei in these are simple multiples 

 of a C5 unit. Thus the terpenes are C5X2, the sesquiterpenes CsXS, whicli 

 multiple also includes the flavone, flavonol, and anthocyan pigments. Phytol, 

 C20H39OH, the alcoholic constituent of the chlorophyll molecule, is C5 x 4, 

 while the closely related pigments carotin, C40H56 and xantliophyll, C40H56O2, 

 are based on C5 x 8. It is suggested as a plausible hypothesis that the C5 unit 

 is formed by oxidation of w-hydroxy methyl furfuraldehyde, which is derived 

 from the primarily synthesised hexose by loss of water. If the possibility of the 

 production of furane derivatives in this way be admitted, then the conversion 

 of these into pyrroles by means of ammonia or methylamine could readily take 

 place by perfectly straightforward reactions. 



((') Dr. F. C Eve. — Photosynthesi.i from the Energy Aspect. 



Friday, September 8. 



5. Prof. J. McLean Thompson. — The Meaning and Evolution 



of Some Floral CJiaracters. 



The origin, meaning, and modification of systematic characters claim intensive 

 study. The structural expressions of such characters demand developmental 

 inquiry linked with exact knowledge of the chemistry of the cell. 



In the present communication certain structural aspects of the origin and 

 development of floral characters were discussed. The origin and meaning of 

 the characters themselves are subjects of speculation. The aim in view is to 

 point to the need of study of the changing cell-chemistry from the initiation of a 

 systematic character to its establishment. It is held that by such study a 

 knowledge of evolution may be materially advanced. 



6. Mr. J. Walton. — The Physiological Anatomy of the Fossil Genus 



Ehexoxylon compared witli that of some ynodern Lianes. 

 The genus Rhexoxylon (Bancroft) shows features in the distribution and 

 histology of its xylem analogous to some which appear in modern lianes, in 

 particular to certain members of the Malpighiaceae. Rhexoxylon occurs in beds 

 of the Stormberg series of South Africa, and the name Antarcticoxylon (Seward) 

 of a fossil stem from the Beacon Sandstone, S. Victoria Land, must be regarded 



