CHAPTER XI. 



ARRANGEMENT OF THE SECRETORY 

 RESERVOIRS. 



Sect. 130. The primary arrangement of the secretory reservoirs presents little 

 of interest, and it has often been impossible to avoid the mention of it in preceding 

 sections. The present Chapter, which is necessary simply for the sake of consistency, 

 must therefore be a short one, and confine itself chiefly to references to former 

 paragraphs. 



The sacs containing crystals lie, in the plants enumerated in Sect. 31, to which 

 they are peculiar, in the primary parenchyma, sometimes ' scattered ' between its 

 cells, sometimes more regularly distributed, or at definite places in definite grouping. 

 On their distribution in the pith of Dicotyledonous woody plants, see p. 403 ; on 

 their accumulation on the wall of the air-passages of Water-plants, Aroidese, &c., 

 comp. p. 219 ; on the series of raphides accompanied by mucilage in the Mono- 

 cotyledons, see p. 1 39. It may here be mentioned more definitely than was done in 

 S^ct. 31, that the vascular bundles are occasionally, but by no means universally 

 accompanied by series of elements containing crystals; e.g. the petiole of Cycas 

 revoluta (p. 336) ; and the medullary bundles of Melastomacese, as Heterocentron 

 and Centradenia spec, with longitudinal rows of sacs containing crystalline aggrega- 

 tions on their outer side, &c. 



The sacs containing mucilage lie in the primary parenchyma of the plants men- 

 tioned at p. 143, and in fact principally in the foliage and cortex, usually scattered 

 without any generally determinate order; their more regular distribution in the 

 tubers of Orchis has already been mentioned at p. 144. 



The same scattered position in the primary parenchyma of the foliage, pith, 

 and especially of the cortex, prevails in the case of the short sacs containing resin and 

 gum-resin, of the families mentioned at p. 145. 



The long sacs of this category, and the tannin-sacs, have already been discussed 

 at p. 146, &c. Comp. further Sect. 48, especially p. 199, and Chap. XII. 



