HYACINTH ROOT 179 



different form (calcium sulphate, which is not readily soluble) 

 may be seen to be formed in the fluid. 



These reactions, coupled with what can be ascertained from 

 analysis of the ash of the plant, point to the conclusion that 

 these crystals consist of calcium oxalate. 



Cut transverse sections of the petiole of some species of 

 Begonia ; mount in water, and examine under a low power. Here 

 and there will be found bodies of a more or less distinctly 

 crystalline form occupying the cavities of certain cells. Their 

 form is very complicated, and their size variable. 



The reagents above applied to the Hyacinth are to be used : 

 the results will be similar. Thus they also may be shown to 

 consist of calcium oxalate. Crystals giving the above reactions 

 will be found in the tissues of most plants. 



TYPE. 



Examine the leaves of the common Iris (I. Pseud- 

 acorus), and note the lower sheathing or equitant part, 

 and the upper, laterally copmressed, ensiform portion. 

 Cut transverse sections of the latter, mount in glycerine, 

 and observe the general disposition of the tissues, as 

 follows : 



1. On either surface a layer of epidermis with 

 stomata. 



2. Beneath each epidermis a band of chlorophyll- 

 containing parenchyma, which gradually merges 

 into 



3. A central mass of colourless parenchyma. 



4. Distributed somewhat irregularly are numerous 

 vascular bundles of various size ; sometimes they are 

 arranged opposite one another, sometimes alternately. 

 Note especially that their orientation is such that the 

 phloem (usually bounded by a band of sclerenchyma) is 



N 2 



