53° 



SECONDARY CHANGES. 



(a) Both in the medullary rays and in the bundles : Nerium Oleander (K), Shnaruba 

 officinalis (K), Canella (C), Platanus, Cinnamomum zeylanicum and its allies (small 

 raphides, chiefly in the medullary rays), Juglans regia (C, Sanio), Acer platanoides (K), 

 Sparmannia Africana (C), Carpinus Betulus, and Corylus Avellana (K, C, Sanio). 



(b) In the bundles, exclusively, or to much the greater extent : species of Salix (G, K), 

 Pyrus communis (K), Punica {C),- Ribfes (C), Guaiacum (K), Galipea officinalis (R, 

 K), Madura aurantiaca (K), Ulmus (K)-, Quillaia (K), iEsculus (K), Rhamnus Frangula 

 (C), Quercus pedunculata (K, C), Betula verrucosa, Alnus glutinosa (K, C, and 

 granules, Sanio), and Porlieria hygrometrica (K). 



(f) Exclusively, or to much the greater extent, in the medullary rays, and when the 

 latter ar#of considerable breadth, most abundantly at their boundary towards the 

 bundles-,' Vitis (K, R), Tilia (K, C), Cheirostemon (C), Olea europaea (very small R), 

 Ficus elastica (K), Croton Eluteria (C), Pistacia Lentiscus (C), Prunus Padus (C, K), 

 P. avium (C), Kerria japonica (,G), Berberis vulgaris (scanty K according to Sanio), 

 Lonicera tatarica (Sanio), and Sambucys nigra (granules, Sanio). 



The crystal-containing sacs, especially those which are septate and contain 

 klinorrhombic crystals, appear in many cases in company with the bast-fibres, as 

 pointed out by Schacht^- e.g. species of Acer, Pomacese, Ulmus, Quercus, Salix, 

 &c.^ Clusters often odcur exclusively and in large quantities where fibres are 

 absent, e.g. Punica and Ribes ;' though the entire absence of the tissue last- 

 mentioned may also occur in connection with the entire absence of crystals, e. g. 

 Drimys Winteri. 



No constant relation however exists between the presence or absence of the two 

 forms of tissue mentioned, or between any definite form of tissue and of the crystals, 

 as is evident from the facts stated. Thus klinorrhombic crystals are especially often 

 present in abundance where fibres are absent in the secondary bast, e. g. Porlieria and 

 Nerium; while, on the other hand, the klinorrhombic companions of the fibrous bundles 

 are absent in Juglans regia and many other cases. And further, where the fibrous 

 bundles are accompanied by crystals, the occurrence of the same or another form of 

 crystal in the soft bast is by no means excluded. 



In the soft bast the rows of sacs containing crystals have in most cases an 

 irregular, scattered position in the transverse section. On the other hand, they are 

 often arranged in concentric zones, which alternate regularly with zones destitute of 

 crystals. This is the case in Punica Granatum, where the whole bast appears 

 regularly striated, in transverse section, owing to the fact that uniseriate zones, con- 

 sisting almost exclusively of crystal-sacs, alternate with zones each consisting of a 

 few rows of cells, which are destitute of crystals ; these zones are interrupted by 

 numerous uniseriate medullary rays, which are also destitute of crystals (corap. 

 Fig. 215, and the beautiful figure in Berg, Atlas, Taf. 40, which however is not quite 

 correct in the details). In species of Ribes also, the bundles, which are separated by 

 broad medullary rays without crystals, consist of multiseriate zones of soft bast, like- 

 wise destitute of crystals, which alternate regularly with usually uniseriate uninter- 

 rupted zones, containing clustered crystals '. 



Sect. 167. As regards the changes of structure corresponding to the successive 



' Der Baum, i Anfl. pp. 228 and 238. " Compare Sanio, /. c. 



^ Compare Hansteia, Baumrinde, Figs, 15-17. 



