641 
Growth and Structure of the Wood of Larix, 
7. The same ring may show remarkable differences in the autumn 
wood formation on opposite sides of the tree, and in such a way as must 
be referred to the positions of the different branches, pending further 
investigations. 
8. The outermost cells of the autumn wood may have their walls 
unthickened, though those farther inside may be normal in this respect. The 
lack of thickening in the outermost cells might be referred to changes in the 
rate of the transpiration current during the development of the autumn wood. 
For defoliation would cause stagnation in the tracheides ; whereas on the 
other hand the new growth of leaves that often follows after defoliation 
might make renewed demands on the water supply and stimulate the 
cambium to the production of thin-walled conducting cells. 
9. Other examples give evidence rather that the outermost cells 
are unthickened merely because food ran short at the close of the year. 
The small size of the cells concerned supports this view, namely, that they 
are not a new formation of conducting tissue , but merely the ‘ mechanical } 
cells of typical ' autumn wood ’ starved in development. 
10. Abnormally formed resin ducts have been remarked in the defoliated 
larches ; possibly they are causally connected with the starvation, as 
a pathological effect. 
Magdalen College , Oxford , 
Dec., 1912. 
References to previous Publications. 
1 . Ann AND : Quarterly Journal of Forestry. 1910. 
2 . Haberlandt, G. : Physiologische Pflanzenanatomie. 1884. 
3 . Hartig, R. (1) : Holz der deutschen Nadelwaldbaume. 1885. 
4 . ( 2 ): Holzuntersuchungen. 1901. 
5 . ( 3 ): Lehrbuch der Anatomie und Physiologie der Pflanzen. 1891. 
6. FIewitt : Journal of the Board of Agriculture. 1908. 
7 . Krabbe, G. : Sitzungen der Berliner Akademie. 1882. 
8. Lutz, K. G. : Beitrage zur wiss. Botanik, herausgegeben von Fiinfstiick, i. 1. 1895. 
9 . MacDougall : Journal of the Board of Agriculture. 1906. 
10 . Nordlinger : Der Holzring. Stuttgart, 1872. 
11 . Pfeffer, W. ( 1 ): Physiology of Plants, vol. ii, 2nd Eng. ed. 1903. 
12 . ( 2 ): Pflanzenphysiologie, Bd. i, Aufl. 2. 1897. 
13 . Ramann, E., und Bauer : Jahrbuch fiir wiss. Botanik. 1911. 
14 . Record, S. J. : Economic Woods of the United States. 1912. 
15 . Sachs, J. ( 1 ) : Lehrbuch der Botanik, Aufl. 1. 1868. 
16 . ( 2 ): Vorlesungen liber Pflanzenphysiologie. 1882. 
17 . Sanio : Pringsheim’s Jahrbucher fiir wiss. Botanik. 1872. 
18 . Schwarz, F. : Dickenwachstum und Holzqualitat von Pimts sylvestris . 1899. 
19 . Strasburger, E. : Leitungsbahnen. Histologische Beitrage, iii. 1891. 
20 . Thomson, W. P. : Botanical Gazette. April, 1912. 
21 . Tschirch, A. : Harz und Harzbehalter. 1906. 
22 . WiELER, A. : Jahrbuch fiir wiss. Botanik. 1887. 
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