752 NOTES 



convenience and precision. In addition to the medullary rays. Sanio recognises three 

 classes of component elements, viz. : I. Parenchymatous system (1) Xylem-paren- 

 chyma ; (2) Intermediate cells. II. Fibrous system (1) Non-septate wood-fibres 

 (libriform cells); (2) Septate fibres. III. Tracheal system (1) Tracheides ; (2) 

 Vessels. 



353. Leclerc du Sablon : Rev. gen. d. Bot. 1904. Schellenberg : Ber. 23, 1905. 



354. Th. Hartig : B.Z. 1858. A. Fischer : P.J. 22, 1891. 



355. Strasburger (Leitungsbahnen, pp. 486 sqq.) only recognises two types of tissue 

 in the woody cylinder, namely, tracheal tissue and parenchyma, and assumes that 

 the mechanical elements are phylogenetically derived from members of these two 

 other systems. It is, of course, quite possible that this view is correct, though the 

 facts detailed in the text hardly seem to support it. Strasburger's statement (I.e. 

 p. 468, Note) to the effect that the author erroneously derives fibrous tracheides 

 from wood-fibres, on physiological grounds, although the two kinds of cell have 

 really nothing to do with one another, is founded on a misconception. Strasburger 

 forgets that the present work is written from the anatomico-physiological, and not 

 from the phylogenetic point of view. The transitional series in the table on p. 664 

 might therefore just as well be read in the opposite direction. Moreover, while the 

 author includes all the mechanical elements of the wood in the category of wood- 

 fibres, whatever their phylogenetic origin may be, Strasburger restricts this term 

 to those fibres which he believes to be derived from xylem-parenchyma ; from 

 Strasburger's point of view, therefore, it would naturally be absurd to attempt to 

 derive fibrous tracheides from wood-fibres. As a matter of fact, the author stated 

 quite plainly in the first [German] edition of the present work that his transitional 

 series must not be interpreted in a phylogenetic sense. 



356. Russow : Bot. Centr. 4, 1883. Cf. also Klebahn : Ber. 1, 1883. 



357. Troschel : Unters. ub. d. Mestom im Holze d. dikot, Laubbaume (Inaug.- 

 Diss.), Berlin, 1879. Krah : Ub. d. Verteil. d. par. Elemente im Xylem u. Phloem 

 d. dikot, Laubbaume (Inaug.-Diss.), Berlin, 1883. 



358. P. Schulz : Das Markstrahlengewebe u. seine Beziehungen z. d. leit. Ele- 

 menten d. Holzes (Inaug.-Diss.), Berlin, 1882. 



359. Pfeffer : Physiology, 1, p. 262. 



360. A. Fischer : P.J. 22, 1891. 



361. The formation of "annual" rings in tropical woody plants is evidently 

 a somewhat complicated problem. Cf. Reiche : P.J. 30. Ursprung : B.Z. 1904. 

 Holtermann : Des Einfluss d. Klimas auf d. Bau d. Pflanzengewebe, Leipzig, 1907. 



362. Kny : Ub. d. Dickenwachstum d. Holzkorpers in seiner Abhang. v. auss. 

 Einfl. Berlin, 1882 (and the literature there cited). Wiesner : Sitzb. Wien, 101, 

 1892. Id. Ber. 13, 1895. R. Hartig : Holzuntersuchungen, Berlin, 1901. Ursprung : 

 Ber. 19, 1901. Id. Beih. Bot. Centr. 19, 1905. Id. Biol. Centr. 26, 1906. Sonntag : 

 P.J. 39, 1904. Metzger : Naturw. Zeitschr. f. Forst- u. Landw. 1908. 



363. According to R. Hartig and Sonntag, the white and red wood of Conifers 

 differ also in histological characters. In the case of the Spruce, the red wood is more 

 highly lignified, and the slit-like cavities of its bordered pits are more elongated and 

 less inclined, than those of the white wood ; the stratification of the walls is also 



