SECTIONAL TRANSACTIONS.— K. 621 



tract (6) medullation, i.e. replacement of tracheides bv living pith-cells ; (c) «/e/Za<,cm 

 the^vr/n,1 ^'^f -;f-« ; (<^) vfio- combinations of these^eading to seglegal^f 

 w«1l fS /if 'f". P^'*'-, ?^^^ enveloping tissues, and often the endodermis aa 

 Tacis The re,',S, "^ r^ *^' '^ '^"' ^""'l'"^ *°"'^^''^ segregation of whole vascular 

 u A . ^^" , '^ ^"^ intimate relation of conducting and parenchymatous tissues 

 such that as a rule each tracheid abuts at some point on a living ceH Th sTn 

 S ,11 ^''"^^t^^e.f^^te : 't '«. however, normal in all secondary wood, by reason o" 

 medullary ra,ys with or without wood-parenchyma. Accordh.gly the physiologies 

 Mw"o' ^l th^.«'^«-f'^f°'- '^ automatically met where secondary conducting tisluee 

 Sherspeakers^"'"'"'^ structure. The discussion of (1) and (2) is left to the hands of 



Afternoon. 

 Joint Discussion with Section D on A Biological Investigation of British 

 Fresh Waters. (Prof. F. E. Fritsch ; Mr. R. Gurney ; Mr J 

 Omer Cooper ; Prof. D. Ellis ; Dr. B. M. Griffiths ; Miss P M 

 Jenkin ; Mr. J. L. Saqer ; Mr. J. T. Saunders ; Mr. A. Malins 

 Smith.) 



vpr^W ^' ^•/^"^^^•-tI? spite of the large area of fresh waters in the British Isles, 

 27^t7^. l^ T^!T °{ t^i^i' biology are being undertaken. Of our many streams 

 and of the big stretches of the Broads very little is known in this respect. During 

 «t,?H?nfV>'^'? of this century the Wests had laid the foundations for a detailed 

 study of British lakes, but this work, though it has proved to be fundamental, has 

 not been pursued to an extent at all comparable with the promising nature of the 

 mitial results In fact, many aspects of limnology are altogether neglected in this 



p^wZ'^^'n ll^P^i'^' u^^^ *° ^^^ phytoplankton, which has received most 

 attention. On the other hand, on the Continent and in the United States of 

 America, a host of workers are dealing with the more or less self-contained biotic 

 systems that are constituted by lakes. A number of lake-types (oligotrophic, 

 eutrophic, dystrophic), characterised by their fauna and flor^ and thi general 

 Pfy'?'^' """fit'^.f '. ^^''^ been distinguished, and these are evidently reprlsented 

 also m Great Britam, where a study of the transitional types seems likely to be of 

 special mterest. Fresh-water habitats in part present analogous problems to 

 those encountered in the sea, and a more intensive investigation of British fresh 

 waters will no doubt help in the solution of problems of marine biology. There is 

 also a possible economic bearing in relation to fresh-water fisheries. Great Britain 

 lacks a fresh-water biological station, comparable to that of Plon in Germany and 

 u ^"^ f^"?*"*' but, in order to initiate and stimulate limnological investigations 

 such a station ha,3 become an urgent necessity. Opinions will differ as to the most 

 suitable site and the source of the necessary funds, but there will be general 

 agreement that such a station is wanted. 



Mr. R. W. Butcher.— J Method of Studying the Diatoms of Streams and 

 some of the Results obtained. 



Mr. N. W. Barritt.— T^e Growth and Nutrition of Cotton Seed Hairs. 



It is generally assumed that cotton hairs in growing out from the epidermis of the 

 seed coat obtain their food supply from within the seed. 



*i.-J^^'j®'^''® ¥^ °°"^ ''^^^ obtained to show that this is possible only during the first 

 tliirty days of growth, and that during the remaining twenty days required for 

 secondary thickenmg the food supply can only be obtained from the cayity of the 

 boll or capsule. -^ 



This theory is discussed in relation to the occurrence of branched hairs, insect 

 attack, and subsequent spinning quality of the lint. 



Department op Forestry. 

 Dr. J. D. Sutherland, C.B.E.— Deer Forests : Percentage flantahle. 



A short history of the origin of deer forests, of their uses and attributes past and 

 present. An examination of their condition and of the possibilities of utilising such 



