NOTES 723 



to bending"; similarly, w inextensibility " signifies (Ik- "property of offering 

 resistance to stretching," not the property of being unstretchable. A list of all 

 the terms of this kind used in the present work, their meanings and ( Jerman equi- 

 valents, is given in the foregoing table.] 



[96a. p. 165. The correct equivalent of neulrale Faser is " neutral lamina," 

 p. 166. The designation of the axis common to the several I-girders in Fig. 55 

 as their "common neutral axis" (gemeinschaftliche neutrale Achse) is not strictly 

 in accordance with British usage. I am indebted to Professor J. D. Cormack for 

 the information upon which the present note and Note 94 are based.] 



97. Potonie : Kosmos, 6, 1882, pp. 181 sqq. (corrugated structure of stereome). 



98. Stereome in Palm leaves. Stahl : Ann. Buit, 11, 1893, p. 172. Koop : Beih. 

 bot. Centr. 22, I. 1907. Koop believes that the thinness of the lamina and the 

 lowness of its girders are sufficient to account for the unusual flexibility of the leaves 

 of Palms ; if this were the case, it would be difficult to understand why the fibrous 

 strands are so often deeply embedded in the mesophyll in this group. 



99. Worgitzky : Flora, 70, 1887 (tendrils). 



100. Magocsy-Dietz : Math. u. naturw. Ber. Ung. 17, 1901 (septate pith). 



101. Protection of intercalary meristems. Westermaier : Monatsber. Berlin, 1881, 

 pp. 67 sqq. Id. Mitth. naturf. Freib. 1901. 



102. Westermaier u. Ambronn : Flora, 1881 (inextensibility of climbing stems). 



103. Warming : Engler's Jahrb. 4, 1883 (buttress-roots of Rhizophora). 



104. Protection of leaf- margin. The observations on this subject published by the 

 author in the first [German] edition of the present work have been greatly extended 

 by Hintz (Nova acta, 54, 1889.) Cf. also Lippitsch: Ost, bot. Zeitschr. 1889 

 (Musaceae, etc.). 



105. Sachs (Lectures, p. 50) attributes the function of protecting the leaf-margin 

 against the risk of tearing more especially to the marginal commissures between 

 the lateral veins ; in large or delicate leaves there are often several of these com- 

 missures one behind the other. " The leaf-margin is then comparable to a railway 

 viaduct constructed of two or three storeys of arches; a comparison which is by 

 no means a merely superficial or formal one, but completely describes the fact 

 itself, since this mechanical arrangement of the venation has a similar mechanical 

 significance to that of the arch-piers of a bridge." As a matter of fact, the simi- 

 larity upon which Sachs lays stress is purely superficial. For the arches of a 

 viaduct have to resist the vertical pressure of the traffic passing over it, whereas, 

 in the case of a leaf, the wind exerts its shearing action in a plane at right angles 

 to that of the marginal commissures. If the leaf had to withstand pressure against 

 the margin, which is not the case then its structure might indeed be justly com- 

 pared to that of a viaduct. 



106. C. Miiller : P.J. 19, pp. 497 sqq. (clamp-cells of Equisetum). 



107. Influence of meclianical stimuli on the development of stereome. Knight : 

 Phil. Trans. 1803, II. p. 280. Id. ibid. 1811, p. 217. Treub : Ann. Buit. 3. Pfeffer : 

 Ber. sachs. Akad. 1891, pp. 638 sqq. Wiedersheim : P.J. 38, 1902. Vochting : 

 Nachr. Gott. 1902. Unters. z. experim. Anat. u. Path. d. Pflanzenkorpers, Tiibingen, 

 1908. Ball : P.J 39, 1903. Bucher : P.J. 43. 1906. 



