BOTANY 369 



BOTANT. By E. J. Salisbury, D.Sc, F.L.S., University College, 

 London. 



Ecology. — -The contradictory results that have been obtained 

 by various workers with regard to the effect of varying 

 transpiration rates on the ash content of the plant, has led 

 Muenscher (Amer. Jour. Bot., pp. 311-29, 1922) to test the 

 matter on Barley grown in culture solutions, the rate of 

 transpiration being reduced by either (i) increasing the atmo- 

 spheric humidity ; (2) decreasing the illumination ; or (3) in- 

 creasing the concentration of the nutrient medium. Decrease 

 of the rate of transpiration to less than one-half by the first 

 method caused but little variation in the ash content. A 

 slight reduction was effected by the third method, but when 

 the reduced transpiration was brought about by the second 

 method, which also reduced assimilation, the ash content was 

 proportionately diminished. 



A forest consisting of Pinus contorta with an undergrowth 

 of Ledutn grognlandicutn and Gaidtheria shallon, which has 

 become established on an old Sphagnum bog, is described by 

 G. B. Rigg {Ecology, vol. iii, p. 207). The substratum is 6-12 

 inches of pine needles resting on about 1 2 inches of Sphagnum, 

 and followed by a fibrous peat with a high water content. 

 The succession to forest appears to have been hastened by 

 drainage, and the clearance of the surrounding area. 



The relation of maritime soils to their vegetation is the 

 subject of a paper by Salisbury {Ann. Bot., vol. xxxvi, pp. 391- 

 431), in which it is shown that in both dune soils and those of 

 shingle beaches the reaction tends to become more acid with 

 increasing age and there is a diminution of carbonates and an 

 increasing organic content. In the dune soils the relation 

 between the organic content and the water capacity is a close 

 one. In the salt marshes also there appears to be an increase 

 of organic content with age, but here the duration and frequency 

 of tidal inundation seems to be the chief factor to which the 

 vegetation responds. 



On the dunes and shingle beaches the sequence of phases 

 in the vegetation would appear to be correlated with the 

 edaphic sequence with respect to soil stability, reaction, car- 

 bonate and organic contents. The acid reaction is a result of 

 the organic material present and varies with the source and 

 the phase of decay which this has attained. 



Geographical Distribution, etc. — In an account of the flora 

 of the Pliocene beds of the Rhone valley corresponding in age 

 to the Coralline Cragi and Norwich Crag, G. Depape makes^an 

 important contribution to the geographical distribution of 

 the past and its relation to that of the present {Ann. d. Sci. 

 Nat. Tx., pp. 73-265). Seventy species are enumerated, of which 



