44 



growth of this oak is really very astonishing 

 Danckelmann r tell us that some full-grown trees 

 reached in the course of 50 to 55 years quite, 

 and occasionally more than, 24 metres in height 

 and 50 centimetres in diameter. Eberts 2 tells 

 us the same thinor about the Government District 



o 



of Aachen, and Lorey 3 from Wurttemberg. Dr. 

 Eichhorn4 makes out that up to its fiftieth year 

 the red oak produces a greater quantity of wood 

 than the home oak but from that period decreases, 

 and Hartig 5 gives us the same information about 

 trees one hundred years old. The investigations 

 made by Mayr 6 show that wood grown in 

 Germany possesses a specific gravity in the sap- 

 wood of 64, heart 67. German oak, given the 

 same breadth of rings, has a specific gravity of 67 

 or 70. Nordlinger7 estimates a special gravity 

 of only 60 for timber having rings of one milli- 

 metre in breadth. The contents of tannin in 



1 " Anbauversuche mit auslandischen Holzarten in den 

 preuszischen Staatsforsten," "Z. f. F. u. Jw.," 1884, p. 370. 



2 "Verhalten einiger fremdlandischer Holzarten im Regier- 

 ungsbezirke Aachen," "Z. f. F. u. Jw.," 1892, p. 267. 



3 Lorey, I.e. see previous pages. 



* " Untersuchungen iiber das Holz der Roteiche," "Forstl.- 

 naturw. Z.," 1895. 



s " Ergebnisse der Anbauversuche in Bayern," " Forstl.- 

 naturw. Z.," 1892. 



6 L.c., 1884, p. 129. 



7 Literarischer Bericht iiber " Les chenes de I'Amerique 

 septentrionale en Belgique," "A. F. u. Jz.," 1888, p. 95. 



