11 



half the genera of this order providing species of weeds. On the 

 other hand, Rosacecc and Legiiminosoe supply very few weeds. 



The important problems connected with quality of crops are now 

 under investigation. For some time past we have been studying 

 the herbage of grazing land and found that the conventional methods 

 of analysis failed to distinguish between poor herbage and highly 

 nutritious herbage that fattened sheep without artificial food. In 

 other investigations at Rothamsted the conventional methods have 

 equally failed and it has become necessary to go into the problem 

 systematically and improve our knowledge of what confers "quality" 

 on crops. 



This work has now been put in hand. Mr. Davis is engaged 

 on an exhaustive study of the constituents of the commoner crops 

 and has begun by investigating the nature and amount of the various 

 sugars present. The analytical difficulties are very considerable, and 

 unsuspected sources of error have been revealed in some of the 

 methods in use. In particular the addition of basic lead acetate in 

 relatively large proportions for eliminating amino-acids, tannins, etc., 

 gives rise to difficulties in estimating cane sugar, because the sodium 

 acetate, formed when the lead is removed by sodium carbonate, pro- 

 tects the sugar from inversion by weak acids. Objection can 

 similarly be raised against other methods, but the progress that has 

 been made up to the present fully justifies the hope that a satis- 

 factory solution will be found of the various difficulties encountered. 



The following papers have been published during the year. 



• Winifred E. Brenchley. ''The Weeds of Arable Laud 

 ill relation to the Soils on whic/i they grow.'' II. Annals of 

 Botany. 1912. 26,95—109. 



This investigation was conducted during the season of 1911 at 

 several centres in Wiltshire and Somersetshire, and the results are 

 compared with those obtained in Bedfordshire in 1910. 



A general resemblance can be traced both as regards distribu- 

 tion and variety of the species, but there were notable exceptions. 



In Bedfordshire, Bartsia Odontites is typically confined to 

 clay and is not seen on the chalk ; in the west country it occurred 

 chiefly on the chalk. Matricaria inodora, very plentiful in Bedford- 

 shire, was not found in the west. Capsella Bursa-pastoris, 

 Euphorbia exigiia and Tiissilago Farfara were chiefly found on 

 clay in the west ; in Bedfordshire, on the other hand, the first two 

 were rarely found on clay, while the third occurred on all types of 

 soil. Of the so-called Calcifuges of the Bedfordshire soil, Poa 

 annua alone retained that character in the west, the others, 

 Alopecuriis agrestis, Anagallis arvensis, Chenopodiiini album, 

 Euphorbia exigua, E. helioscopia, E. peplus, Veronica arvensis, 

 V. hedercefolia, all flourished on the chalk there. On the other 

 hand, several plants occurring on vaiious types of soil in Bedford- 

 shire are definitely associated with chalk soils alone in the west. 

 Some of these differences in behaviour may be influenced by the 

 character of the seasons, 1910, when the observations were made in 

 Bedfordshire, having been cold and wet, while 1911, when the 

 western observations were made, was unusually hot and dry. 



