236 JOURNAL OF THE ARNOLD ARBORETUM (vol. ti 



very slowly. The broadleaf trees grow under a variety of shade and soil 

 conditions and their roots ramify in all directions. I pulled up seedlings 

 and small plants (I have them dried) of every Taxad and Conifer I came 

 across and in every case found the roots clothed with tubercles. I did 

 the same with the broadleaf trees but found no tubercles present. My 

 attention was directed to the presence of tubercles on the roots of Taxads 

 and Conifers Ijy Captain L. Macintosh Elhs, the Director of the Forests. 

 Later I found that their presence was known to others but the signifi- 

 cance does not appear to have been grasped by anyone but by the Director 

 of Forests and no investigations of this phenomenon have been attempted. 

 The tubercles are analogous witli tliose on the roots of leguminous plants 

 and in all probability the bacteria break up the raw humic acids and con- 

 vert them into readily available salts. It is a simple and beautiful case of 

 symbiosis but I have no knowledge of such in our northern Taxads and 

 Conifers though it is known in the case of the Alders and a few otlier broad- 

 leaf trees otlier than Leguminoseae with which it is general. This discovery 

 is important for, if I am right in my conclusions, the organisms within the 

 tubercles are controlling factors in the rate of growth of the Taxads and 

 Conifers of New Zealand. As evidence let us consider what happens in 

 the forests. The lumberman fells and removes the merchantable trees 

 thus opening up the forest floor to the full influence of the sun and wind. 

 The peaty soil quickly dries, fires come up and destroy not only the re- 

 maining growing vegetation but also the peat and the organisms in it 

 thereby rendering the very soil virtually useless for the regrowth of the 



Taxads and Conifers, When plants of these trees are placed in ordinary 



garden soil there is no humic acid present even if there l^e tubercles on the 

 roots of the plants when brought from the forest and consequently they 

 merely linger and their growth is very slow without the acid of the sym- 

 biotic organisms. This, I believe, is briefly the whole story of the poor 



regeneration and slow growth of the Taxads and Conifers in the cut over 

 forests of Xew Zealand. 



Hob ART, Tasmania, March, 1921. 



BIBLIOGRAPHICAL NOTES 



Ethelyx M. TrrKER 



Hempel und Wilhelm. Baume und straucher des waldes. The 



inclusive dates of the three abtheilungen of **Die baume und straucher 

 des waldes in botanischer und forstwirthsehaftlicher bozichung, von Gus- 

 tav Hempel und Karl \YiIhehn'* are readily found to be 1889 to 1890. 

 The dates of publication of the twenty lieferungen forming these ab- 

 theilungen are, however, not obtained so easily and are worthy of notice. 

 From Botainsche zcitung and Oesfcrreichische botanische zeitschrijty with 

 occasional reference to Flora for these years, the dates and pages included 



