852 JOURNAL or 1-ORESTRY 



and thorough knowledge of this complex phenomenon, of which the 

 m\'stery is almost as deep as the mystery of the life, still remains for 

 further investigations. Yet some commqnly accepted views as to the 

 conditions necessary for its formation may be of assistance in the 

 present investigation. These necessary conditions are the presence of 

 moisture, the contact with air, and the death of cells, so far as we have 

 observed. Among many young trees standing close together, those 

 which had noticeable wounds, mostly at the base of the boles, indicated 

 much earlier production of heartwood than other trees without wounds. 

 This precocious conversion of sapwood into heartwood, together with 

 the eccentric location of heartwood starting from the outward wounds, 

 and its extraordinary irregular form apparently induced by wounds, 

 offers a reasonable explanation of the above view which is found to be 

 exactly applicable to the production of "particular substance." The 

 reason for the difference in color, which is usually noticeable between 

 false and true heartwoods, will be given later. 



DARKENING OF THE HEARTWOOD AND ITS DIRECT CAUSES 



The actual occurrence of this phenomenon may be classified under 

 two heads. The color change takes place in some woods upon their 

 exposure to the air passing through the several stages, while in others 

 the process is more or less completed while the tree is still standing. 

 Although the actual stages of the color change in the latter case can 

 not be observed, they may be supposed to undergo the same process 

 as the former. 



In connection with these stages of the conversion, detailed observa- 

 tions made on a 1 inch board of "black wood" will be given as a 

 typical example. This board was of course of high water content 

 (one of the characteristics of "black wood" as compared with normal 

 "red wood"). Its freshly planed surface was dark red turning to a 



_ Prael. Untcrsuchung von Schutz— und Kernholz der Laubbaume. Disserta- 

 tion, Berlin ISSS. 



Schwappach. Beitrage zur Kenntniss der Qualitat dcs Rothbuchenholzes. 

 Zeits. f. Porst— u. Jagdw., 1894. p. 534. 



Temme. Ueber Schutz— und Kernholz, seine Bildung und seine physiologische 

 Bedeutung. Landwirtsch. Jahrb. Bd. 1, 1885. p. 4r35. 



V. Tcubcuf, C. Normale und pathogene Kernbilduiig der Holspflanzen und die 

 Behandlung von Wunden derselhen. Zeits. f. Forst— u. Jagdw., 1889. pp. 385-,398. 



Tuzson. Anatomische und mikrochemische Untersuchung iiber der Zersetzung 

 und Konservierung des Rothbuchenholzes. Berlin 1905. 



Will. .-\. Beitrage zur Kenntniss der Kern— und Wundholzes. Dissertation, 

 Berlin 1899. 



