APPENDIX 



IN the following pages some important facts not mentioned in the first two 

 volumes are given, and also a summary of the more recent literature, especially that 

 connected with the present volume. 



Action of Rontgen and Radium Rays. Koernicke (Ber. d. D. hot. Ges., Bd. xxu, 

 1904, pp. 148-55) finds that the Rontgen and radium rays slightly accelerate the ger- 

 mination of dry seeds, and retard growth if the exposure is sufficiently intense and 

 prolonged. The retarding effect may remain latent for a time, and may be preceded 

 by a temporary acceleration. 



Correlation and Growth. Lindemuth (Ber. d. D. bot. Ges., Bd. xxn, 1 904, p. 1 7 1) 

 states that the leaves of Begonia rex, of Iresine Lindeni, and of other plants on rooting 

 increase in size, and concludes that this is due to the enlargement of the individual 

 cells. The latter can hardly apply to the non-living cells of the leaf so that internal 

 distorsions or ruptures should ensue in such leaves. 



Ewart (Annals of Botany, Jan., 1906) has shown that by an early removal of all 

 the buds but one, the leaves of the Lime (Tilia europaea) may be caused to develop 

 to twice or thrice their normal size, and that this increase in size is due to an increase 

 in the number of cells in each leaf, their sizes being approximately constant. No 

 growth could be awakened in leaves which had ceased to grow. 



The Phloroglucin Reaction is due to the presence of Hadromal^ an aromatic 

 aldehyde which is destroyed by potassium permanganate or hydroxylamine. 



Wood sections treated with hydroxylamine no longer give the phloroglucin 

 reaction, but if treated for five minutes with i per cent. KMnO 4 , washed with HC1, 

 and then exposed to NH S vapour they turn red, giving a true 'lignin' reaction. 

 Hadromal occurs in many non-lignified cells (hard bast of certain plants, endodermal 

 cells and cork cells). These give no reaction with KMnO 4 , except in the case of 

 the endodermal cell-walls of Iris, which appear to be truly lignified. 



Cleistoganiy. On the causes and occurrence of cleistogamy, see K. Goebel, 

 Biol. Centralbl., 1904, Bd. xxiv, p. 673 seq. See also Klebs, ibid., p. 545 (Ueber 

 Probleme der Entwickelung). 



The Mechanical Properties of the Red and White Wood of Conifers have been in- 

 vestigated by Sonntag (Jahrb. f. wiss. Bot., Bd. xxxix, p. 71), with the following results : 



Length 



Incrusting materials 



Tensile strength of walls .... 

 Resistance to pressure per unit area of wood 

 Comparing walls alone .... 

 Capacity for stretching .... 

 But Modulus of elasticity .... 



Red wood tracheides. 



80* % 



I 

 (walls thicker) higher 



slightly higher 



1.5 to 2-5 % of length 



i 



White wood tracheides. 



60* % 



3 



lower 



slightly lower 

 the same 

 2 (Hartig). 



Branches are as strong in the inverted as in the normal positions, until the 

 limit of elasticity is reached with increasing loads, when the normal position is best. 

 The red wood is more strongly lignified and swells less. It appears on the 



