PRACTICAL SUGGESTIONS UPON TREE-PLANTING. 61 



A sectiou was exhibited by D. C. Scofield, of Elgin, 111., in 1874, 

 which had been imported as a small plant in 1858, and had grown to 

 D^early a foot in diameter in thirteen years. He also exhibited a branch a 

 fourth of an inch in diameter which had been seven years among de- 

 caying rubbish on the ground and was still hard and sound. This test 

 was claimed to demonstrate the remarkable durability of the European 

 larch in the climate of Illinois, while the native species [Larix Americana) 

 would not probably have lasted even half of this time. 



Its rapidity of growth, beauty of foliage, and general value as a 

 screen and ornamental tree have been sufficiently proved in this timber 

 as grown with us. But has its durability as a post, or when in contact 

 with the ground, been proved ? We apprehend that this durability de- 

 pends upon the conversion of sap-wood into heart-wood j a change that 

 has not very often been observed in the larch grown in this country or 

 at least in the West. The Conifers, as a class, are found stronger and 

 of better quality in proportion as their growth has been slow. 



In reference to the law which governs in the formation of wood, it is 

 remarked by Bagneris ^ that in the broad-leaved si)ecies, the vessels of the 

 annual layers of growth are either distributed equally, as in the beech, 

 hornbeam, i)oplars, willows, &c., or are congregated nearly together 

 at the interior of the ring, and are wanting or very small and scattered 

 toward the exterior. This inner or porous layer is of spring growth, and 

 about the same in width from year to year. The outer portion of the 

 year's growth, formed later in the season, and generally called the 

 autumnal layer, is composed of heavy, compact, woody tissue, and this 

 varies in thickness from year to year, being sometimes thick and at 

 others thin. These woods are therefore heavier, denser, and for most 

 uses better in proportion to the rapidity of their growth. To this class 

 belongs the oak, ash, and other kinds which show their rings conspicu- 

 ously in section. Their heart-wood is generally different in color from 

 the sap-wood, being stronger and more durable 5 while in the kinds that 

 have their vessels scattered through the whole growth of the year there 

 is not much difference in color, density, or durability between the heart- 

 wood and the sap-wood. 



But the conifers have no ducts as in most other exogenous woods — their 

 ligneous structure being made up of a peculiar kind of tissue, differing 

 from common wood fiber, which may be known under the microscope by 

 the numerous thin circular spots in the walls of the wood cells. These 

 are found in no other woods except the gymnosperms. The outer margin 

 of the annual layer, is in this class made up of harder and denser tissues 

 than the inner, and this harder part is generally of about uniform width 

 from year to year. The difference in grov/th is expended upon the inner 

 and softer jiortion, and varies in thickness according as the amount of 

 growth has been greater or less. This harder portion on the outer 

 marginof each year's growth gives the wood more strength and durability, 

 at least until the more porous part has been filled by resinous deposits, 

 as in heart-wood. For this reason, conifers of slow, growth, in which 

 these hard tissues are more abundant, have their wood stronger and 

 better for most uses than the fast-growing kinds. 



In visiting the plantation of Mr. 0. D. Scofield, at Elgin, 111., during 

 the last summer, he remarked that his larch, set as posts, scarcely lasted 

 three years. It by no means follows that dura.bility would not be gained 

 with age, and the formation of heart-wood, or that this quality might 

 not be imparted by injecting the timber with mineral salts. 



' Manual of Sylciculiure. Taiuslation by Fernandez and Smythies, p. 31 and 59. 



