Biologie. — Descendenz u. Hybriden. 501 



eingebüsst habe und empfiehlt zu untersuchen, ob in anderen 

 Fällen des Uebergangs von selbstständiger Ernährung zum 

 Parasitismus das Verhalten der Keimlinge ebenfalls vom Sub- 

 strat und eventuell von dessen Pilzen abhängt. 



Büsgen (Hann. Münden). 



Smith, W. G., The Origin and Development of Heather 

 Moorland. (Trans. Roy. Scott. Arbor. Soc. Vol. XVII. 

 1903. Part I. p. 117—121.) 



The majority of heath-areas in N. W. Germany have been deve- 

 loped on the sites of former forests. R. Smith said heather moor ceased 

 at 608 metres practically; then came blueberry (Vaccinium Myrtillus) ; 

 Birch also ceases at about that height. The agreement between the 

 liniits of heath and forests in Scotland suggests the origin of the former 

 from the latter; in many cases this was so The explanation of the 

 conversion of forests of high value into heaths of little value in Ger- 

 many lies in the fact that the forests have been exploited for timber; 

 the failure to reestablish theni is the result of errors in cultivation. 

 Graebner believes that climate and impoverishment of the soil by rain 

 are the causes; but this is limited to open soils already poor in food. 

 Other conditions which cause poverty in the soil are the accumulation 

 of humus and formation of moor-pan („0 r t s t e in") ; this is favourable to 

 heath-growth. The author then describes the formation of raw humus, 

 peat and moor-pan. 



Disforestation is also caused by the influenae of man in disturbing 

 the existing condition of the drainage. Windborne sand may also 

 overwhelm forests or other Vegetation and lead to the development of 

 heath or other sand-types. The regulär burning of grouse-moors is another 

 cause. In the Pennine Chain of England there is less evidence 

 than in Scotland that heather moorland has been derived from ancient 

 forest. 



The natural poverty of the soil itself is only responsible in a few 

 -cases. W. C. Worsdell (Kew). 



BoiiLGER, Q., Some entire-leaved forms of Lamiiim. 



(Journ. of Bot. 1903. p. 150—155.) 



These are L. album var. integrifoüum which, like the type, is found 

 wild at Hamburg, Schleswig and Holstein; L. purpureum var. 

 ocymifolium ; and L. purpureum var. Ändrewsiann. None of these three 

 has any claim to be ranked as a British wild plant. They occur in old 

 herbaria, but rarely in recent ones. W. C. Worsdell (Kew). 



Mallett, G. B., Tiilips. I. Species or Specific Varieties. 



(The Garden. 1903. p. 406—407, 424—425, 441—442.) 



After a brief note on the history of tulip-growing, remarks are made 

 on the cultivation of, the ideal soil for, and the planting of, and the 

 ripening and storage of, Tulips then follows a list and description of the 

 various species and varieties both of garden and wild origin. 



W. C. Worsdell (Kew). 



RiCHARDSON, A. D., The Colorado Variety ofthe Douglas 



Fir. (Card. Chron. 1903. p. 244.) 



There are three geographica! forms of this Pseudotsuga glauca, 

 niacrocarpa, ta.xifoüa. The Colorado variety is hardier than the 

 Pacific form. Sargent makes two varieties of the Douglas Fir: 

 P. mucronata and P. macrocarpa, distinguished chiefly by the size of 



