11 



workers are on active service, but their places are gradually being 

 temporarily filled by volunteer workers. 



The following papers have been published during the year : — 



I. "On the action of certain compounds of Zinc, Arsenic, 

 and Boron on the Growth of Plants." WINIFRED E. 

 Brenchley. Annals of Botany, 1914. 28, 283 — 301. 



Experiments made in water cultures with certain compounds of 

 zinc, arsenic, and boron go to uphold the conclusions arrived at four 

 years ago with compounds of copper and manganese, i.e., that very 

 small quantities of some inorganic poisons stimulate the growth of 

 certain species, but this action is by no means universal. With some 

 poisons the stimulative action is evident, with others it has not been 

 observed ; also, a poison that increases growth in one species does 

 not necessarily do so in another, however small a quantity of the 

 reagent that may be applied. A summary of the conclusions arrived 

 at is as follows : — 



(1) Zinc sulphate in high concentration is very toxic to barley 

 and peas, and no evidence of stimulation has been obtained with any 

 strength of the poison down to a lower limit of 1/200,000,000. 



(2) Arsenious acid is more toxic in its action on peas and barley 

 than is arsenic acid, peas being particularly susceptible. This dis- 

 tinction holds good for sodium arsenate and sodium arsenite, though 

 in a less degree. Again no stimulation is evident with the smallest 

 quantities so far tested. 



(3) Boric acid is less poisonous than zinc sulphate or arsenic 

 compounds, especially with peas. Barley shows stimulation to the 

 eye with some of the weaker strengths of poison, but this is not 

 borne out by the dry weights. Peas, on the other hand, are definitely 

 stimulated with relatively high concentrations of boric acid. The 

 action of the greater strengths of the poison is well marked in the 

 leaves, which tend to become brown, and to die in a characteristic 



II. ' Mapping as an Ecological Instrument" WINIFRED 

 E. Brenchley. Transactions of the Norfolk and 

 Norwich Naturalists' Society, 1914. 9, 723—733. 



The progress of ecological science during the last few years has 

 necessitated the elaboration of special methods of representing and 

 correlating the available facts, one of the most useful of such methods 

 being that of the map, which may now be regarded as a graphical 

 representation of facts from which other facts and hypotheses may 

 be deduced and upon which theories established on a firm basis can 

 be built. A description is given of the various applications of 

 mapping in general use, illustrated by reference to ecological surveys 

 at Erquy (Brittany), and Blakeney Point (Norfolk). The general 

 field map, blocked-in map, grid, transect, and quadrat are discussed 

 and illustrated. 



Some of the methods here described are being applied, with 

 the necessary modifications, to field investigations at Rothamsted. 



