616 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



tarry particles. The conifers appear to be particularly sensitive in this 

 direction. 



The relative amounts of carbon dioxide assimilated by leaves from 

 different stations were calculated and show in a remarkable way the 

 influence of a polluted atmosphere in checking this function. If the 

 amount of assimilation in a leaf from the least polluted area be repre- 

 sented by 100, in the most polluted it was represented by only 11-|. 

 In one case where a dirty leaf assimilated 11^, a similar but cleansed 

 leaf assimilated 19, and in another a dirty leaf assimilated 15, and a 

 similar cleansed leaf 24. This check even in the cleansed leaves is 

 accounted for by the blocking of the stomal openings. 



The influence of acid water upon the growth of grass was also inves- 

 tigated, and it was found that in time the watering with so weak a 

 solution as one part of acid to 100,000 of water (the acidity of the 

 Garforth rain) produced a detrimental effect. The acid had a marked 

 effect upon the chemical nature of the soil, but especially upon the 

 nitrates present, which is accounted for by the inhibition, partial or 

 total, of the nitrifying organisms by the acid in the soil. — F. J. C. 



Begronia *AurOPe.' By J. Gerome (Le Jard. xxv., 589, 264; 

 Sept. 5, 1911 ; 2 figs, and coloured plates). — New winter-flowering 

 begonia. A hybrid of Begonia socotrana and B. Pearcei, closely re- 

 sembling ' Gloire de Lorraine,' but with bright, flame-coloured flowers. 

 The author gives an interesting account of winter-flow^ering begonias 

 in general, and of the principal varieties known in England and France, 

 as well as an historical note on the species to which B. ' Aurore ' ow^es 

 its parentage. — F. A. W. 



Bitter-pit in Apples. Anon. (Gard., Dec. 2, 1911, p. 581; 

 fig.). — This disease has been very prevalent during the past 

 year, not only in soft-fleshed varieties, in which it always occurs 

 more or less, but also in the hard-fleshed ones, though to a less 

 extent. The disease is characterized by small but usually numerous 

 brown spots some distance below the surface, some of which show 

 through the skin. Examination shows no trace of fungus mycelium 

 or bacteria, and the dead spots are to be attributed to some other 

 cause. The dead cells contain starch grains, w^hile the rest of the 

 apple cells contain none, the starch having in the ordinary course 

 been converted into sugar during ripening. This process has been 

 suspended in the case of the dead cells, and therefore the cause of 

 death must have operated before ripening had begun. The prevalence 

 of the disease after this hot summer, and the fact that it is well 

 known in Victoria, Australia, and at the Cape, suggest climatic 

 conditions as the cause ; possibly deficiency of water and accumulation 

 of tannin or malic acid may have led to the death of the cells. 

 Eemedies suggested are attention to the water supply and shading 

 the fruit.— JJ. R. D. 



