APPENDIX. 331 



starch. Raphides are abundant in the garden Ehubarb, 

 Evening Primrose, Balsam, etc. Other forms of crystals 

 ■will often be met with, especially in Begonia leaves, scales 

 of Onion bulb, etc. 



334. For examples of cell-rows the Algae above spoken 

 of must be resorted to. Cell surfaces or single layers of 

 cells are illustrated in the leaves of the Mosses. For 

 eoUenchyma make sections of Potato stems. Dock, Cucum- 

 ber, etc. In the rhizome of a Fern, the Common Brake, 

 {Pteris aquilina) will be found if thin longitudinal sections 

 are made, examples of sderenchyma, as well as of other 

 tissue. It is also illustrated in stony nuts, shells, etc. For 

 primary meristem, longitudinal sections through buds or 

 the growing-point must be made, which consumes much 

 time before success can be expected. Very often the 

 epidermis can be pealed oif, and when spread out and 

 looked at will exhibit the stomates. It is also necessary 

 to make thin sections in order to understand both the 

 epidermis and the stomates. No difficulty will be met 

 with in obtaining different specimens with the jWro-rascM- 

 lar bundles, but scarcely so much can be said as to making 

 sections of them so as to exhibit all the points of structure 

 mentioned in the text. Common cork stoppers can be 

 examined, also the bark of many plants, as Birch, etc., for 

 cork-cells ; in the latter case the walls are thicker. Very 

 small intercellular spaces will be seen, if thin sections of 

 leaves, pith of Indian Corn, etc., be examined with a high 

 power. Large canals are seen often with the naked eye 

 in stems and petioles of many water plants. Resin canals 

 may be looked for in Pine leaves, orange and lemon rind, 

 many of the Labiatse, etc. 



335. When a leafy stem is cut off it wilts unless put in 



