682 THE POPULAR SCIENCE MONTHLY. 



shallow ground it produces more but of less valuable quality. Two 

 needles in one sheath characterize this species. The heart-wood of 

 this pine contains 5*7 per cent of resin, the sap-wood proportionately 

 less. 



The sap-wood of this tree is quickly destroyed when the tree is cut ; 

 it assumes a dark-blue color and rots, through the agency of the myce- 

 lium of a fungus called Ceratostoma piliferum. 



This tree is at present the most valuable and most cultivated tim- 

 ber-tree of Northern Germany. 



The white pine, or common American pine {Pinus strohus), is now 

 also extensively cultivated in Germany, where some forests can be 

 found of trees about a hundred years old. Its wood has the lowest 

 specific gravity of all coniferous wood. In spring, on account of the 

 thinness of its bark, the tree is quickly warmed through, and the wood- 

 cells, formed in the beginning of the spring, are thin-walled ; at the 

 close of the period of vegetation in summer, the annual rings are fin- 

 ished by a few thick-walled narrow cells, thus giving only little thick- 

 ness to the hard part of the annual layer. In amount of resin this 

 pine stands at the head of all conifers, containing 6*9 per cent. The 

 percentage increases up to the age of one hundred years, and with it 

 the quality of the wood. It is of little value when young and erposed 

 to moisture. Pinus cemhra, a native of the Alps and Siberia, forms 

 only small, dense rings every year during the short summers of these 

 regions ; the wood hence becomes heavier, and, although less resinous, 

 more valuable. 



A very valuable tree of Europe is the larch {Larix Enropcea)^ 

 which is native only in the colder regions of Europe and Asia ; its 

 wood consists of narrow annual rings, grown during the short summers 

 of those countries. In the percentage of resin it stands between Pinus 

 and Picea ; its wood is more reddish, like that of the genus PinuSy 

 and its resinif erous ducts are constructed like those of Picea / it con- 

 tains 3'9 per cent of resin. 



Just now, the different German governments are experimenting 

 with the introduction of American trees which, it is expected, will 

 stand the climate and furnish better wood, or, in proportion, a larger 

 quantity, than the German forest-trees now cultivated. One of those 

 of which much is expected is the Douglas spruce {Pseudotsiiga Dou- 

 glasii). Mr, J. Booth, of Hamburg, has cultivated this tree for a 

 long time, and has already some very fine specimens in his park. I 

 was enabled through his kindness to examine its wood carefully ; the 

 specific weight is very much above that of European conifers of the 

 Pinus genus, but not as high as that of the larch ; its quality increases 

 in proportion to the width of its layers — a fact which, until a short 

 time ago, was considered directly contrary to what is the case with 

 wood from European pines. 



Professor Sargeant, of Cambridge, has made the contribution to 



