to grow timber-crops in mixed woods consisting of trees suitable 

 to the soil and situation, and capable of protecting the soil against 

 the deteriorating effects of sun and wind, and in such mixed woods 

 the beech has on the Continent been found to possess the most 

 valuable properties regarding the conservation and the increase of 

 soil-productivity. But with the planting of poor waste land, there 

 can be no sufficient supply of nitrogen without humus; and it is 

 also probably due to the want of any admixture of good humus, 

 that pine and spruce are so apt to become liable to fungous root- 

 diseases when planted on fields thrown out of arable land. 



Dr. AUGUSTINE HENRY. The Study of Trees. The Gardener's 

 Chronicle, N 3614, p. 220. London, April 2, 1910. 



Dr. Augustine Henry, Reader of Forestry at Cambridge Uni- 

 versity, delivered an interesting lecture on the study of trees at 

 Carpenter's Hall, London. Many European trees occur in pairs of 

 species; there are two species of oaks, two of birches, etc. He 

 pointed out that before man changed the face of the country, there 

 were two great classes of land, alluvial flat, and hilly land, and 

 that one of the pair of species grew in the former and the other 

 in the latter. Of the two varieties of oak the only one that had 

 been planted of late years was Q. pedunculata, whereas Q. sessi- 

 liflora was the better one to plant on dry hilly land, since it had 

 hairs on the leaves which prevented excessive evaporation of 

 water. 



A year ago the subject of crossing trees first attracted his at- 

 tention. In studying the Black Poplars, he found that the tree 

 commonly called the Black Italian poplar was in fact a cross between 

 Populus nigra, and P. Deltoida, the American species. The Black 

 Italian grows by far the fastest of the three, making as much as 

 2 cubic feet of timber per year, a fact not to be overlooked by 

 foresters. Its timber is not easily inflammable and would probably 

 pass the tests for fireproof flooring. The astonishing vigour dis- 

 played by the " first cross " is displayed in other cases; Dr. Henry 

 referred to " first crosses " of the willow, the oak, and the elm. 

 Trees could probably be produced by " cross fertilisation " that 

 would show in the first cross very vigorous growth, and he instanced 

 the advantage to the forester of a fast-growing Ash or Walnut: 

 how, in the first generation that vigorous growth would be obtained 



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