908 TRANSACTIONS OF SECTION K. 



converse takes place. The glucose and fructose can easily arise from the inversion 

 of some of the sucrose. If, however, cane sugar he the first carbohydrate to be 

 formed iu the foliage leaf, then the aldehyde theory of photosynthesis becomes 

 less easily imagined. Too little attention appears to have been paid to the 

 possibility of the first sugar of photosynthesis arising in the chloroplast as a 

 product split off from a complex protein aggregate. On this supposition, and 

 granting sucrose as the primary sugar, the still unproven hypothesis of Baeyer, 

 as usually formulated, would scarcely be required. 



Further, greater emphasis in the author's opinion should be laid on the 

 importance of sucrose in the higher plants, and its probable role as the chief form 

 in which the carbohydrate travels in the tissues. Various investigations point to 

 the plant's capability, when calling upon its non-nitrogenous reserves, of con- 

 verting these finally into sucrose before utilising them in growth and metabolism 

 generally. 



In conclusion the author expressed his indebtedness to Major G. Dixon for 

 much assistance in the analytical part of this research. 



5, The Time Factor in Assimilation. By J, M. F. Drummond, M.A. 



6. The Woodlands of Southern England.^ By A. G. Tansley, M.A. 



The more or less vague knowledge that we had of the character and distri- 

 bution of the natural plant communities of the British Isles until the present 

 method of ' primary survey ' of vegetation was initiated a few years ago, requires 

 to be made definite and systematic before it can become of scientific value and be 

 made the basis of furlher research. The present paper was a contribution to that 

 end. Reasons were given for believing that the great majority of existing English 

 woodlands retain enough of their primitive character to permit of their treat- 

 ment as natural plant communities, though nearly all have been modified by the 

 agency of man to a greater or less degree. 



Four main types of natural English woodland were distinguished : The Oak 

 type, the Oak-Birch-lIeath type, the Ash type, and the Beech type. The distri- 

 bution of these, at least in "the south-east" and in the lowlands generally, appa- 

 rently depends entirely on edaphic factors, i.e., on the nature of the subsoil, and 

 each type is characterised by a well-marked composition and constitution. The 

 general character of each was described, the principal dominant and commoner 

 subordinate species enumerated, and the mutual relations of the different types 

 discussed. 



7. The Woodlands of Northern England.^ By C. E. Moss, D.Sc. 



With slight modifications, the scheme of woodland associations described by 

 Mr. Tansley in his paper on 'The Woodlands of Southern England' is appli- 

 cable also to the lowlands of northern England. Woods of the Beech type are 

 not found in the north ; but the remaining types occur, and are determined by the 

 same factors which apply in the south. These factors are chiefly edaphic ones. 



When we come to consider the woods of the higher hills of northern (and of 

 western) England, we find that climatic factors as well as edaphic ones are 

 operative. 



Three main types of woodland occur on the Pennines, viz., Upland Oak 

 Woods, Birch Woods, and Ash Woods. The Upland Oak Woods are dominated 

 by Qttercus sessiliflora. Q. sessilifora Woods occur up to 1,000 feet, and the 

 Birch Woods ascend to 1,500 feet ; they form a natural series, and the presence or 

 absence of the Oak {Q. sessilifora) is determined by altitude. Q. pedunculata 



' A joint paper on ' The Natural Woodlands of England ' will be published in the 

 Annals of Botany during 1909. 



