139 
Xylem of Woody Stems, 
In view of the examination of additional specimens of Fraxinus grown 
in a different situation, my statement with regard to the complete lignifica- 
tion of the fibres requires some modification. Recently I have had the 
opportunity of examining the wood of Fraxinus attacked by Polyporus 
hirsutiis , and found that when the xylem was treated with chlor-zinc-iodine 
the fibre-walls became an intense blue. In accordance with the observa- 
tions previously made, this seemed to indicate a delignification due to this 
parasite. But on examining perfectly healthy shoots from the same tree, 
and also others from trees in the same locality quite free from any fungoid 
attack, it was at once seen that in these cases many of the fibres were only 
partially lignified ; hence the delignification was not primarily due to the 
action of this Polyporus. Local conditions of soil and climate seem in some 
cases to retard the complete development of the xylem, and thus render 
such trees constitutionally weak and very liable to attack. For instance, 
in the particular locality now under consideration very few of the trees 
were free from the infection of Polyporus hirsutus . 
Literature. 
Abromeit, J. (’84) : Ueber die Anatomie des Eichenholzes. Prings. Jahrbiicher fiir wissensch. 
Botanik, Bd. xv, 1884. 
Biffen, R. H. (’01) : On the Biology of Bulgaria polymorpha , Wett., Annals of Botany, vol. xv, 
1901. 
Czapek, F. (’99) : Ueber die sogenannten Ligninreactionen des Holzes. Zeilschr. fiir physiol. Chemie, 
Bd. xxvii, S. 141, 1899 ; Botanisches Centralblatt, Bd. lxxix, 1899. 
(’99) : Zur Biologie der holzbewohnenden Pilze. Berichte der deutschen Botanischen 
Gesellschaft, Bd. xvii, 1899. 
Hartig, R. (’78) : Die Zersetzungserscheinungen des Holzes der Nadelholzbaume und der Eiche. 
Berlin, 1878. 
Hegler, R. (’00) : Histochemische Untersuchungen verholzter Membranen. Flora, Bd. lxxiii, 1890. 
Marshall Ward (’97) : On the Biology of Stereum hirsutum Fr. Philosophical Transactions of 
the Royal Society, vol. 189, 1897, Series B. 
Mayr, H. (’84) : Zwei Parasiten der Birke, Polyporus betulinus, Bull, und Polyporus laevigatus , 
Fries. Botanisches Centralblatt, Bd. xix, 1884. 
Potter, M. C. (’00) : On a Bacterial Disease of the Turnip ( Brassica napus ). Proc. of the Royal 
Society, vol. lxvii, 1900. 
Sanio, C. (’60): Einige Bemerkungen iiber den Bau des Holzes. Botanische Zeitung, Bd. xviii, i860. 
(’63) : Vergleichende Untersuchungen iiber die Elementarorgane des Holzkorpers. 
Botanische Zeitung, Bd. xxi, 1863. 
Schellenberg, H. C. C96) : Beitrage zur Kenntniss der verholzten Zellmembran. Pringsh. Jahrbiicher 
fiir wissenschaftliche Botanik, Bd. xxix, 1896. 
Schrenk, H. VON (’00) : Two Diseases of the Red Cedar, caused by Polyporus juniperinus , N. Sp., 
and Polyporus carneus , Nees. U. S. Department of Agriculture, Bulletin No. 21, Washington, 
1900. 
• (’93) : A Disease of the White Ash, caused by Polyporus fraxinophilus. U. S. De- 
partment of Agriculture, Bulletin No. 32, Washington, 1903. 
Singer, Max (’82) : Beitrage zur naheren Kenntniss der Holzsubstanz und der verholzten Gewebe. 
Sitzungsber. d. Wiener Akad., Bd. lxxxv, Abt. i ; Botanisches Centralblatt, Bd. x, 1882. 
Strasburger, E. (’91) : Ueber den Bau und die Verrichtungen der Leitungsbahnen in den Pflanzen. 
Jena, 1891. 
Wisselingh, C. van (’98) : Microchemische Untersuchungen iiber die Zellwande der Fungi. 
Pringsh. Jahrbiicher fiir wissenschaftliche Botanik, Bd. xxxi, 1898. 
