LIST OF PLANTS USED FOB STUDY. 471 



Primrose. See Primula. 



Primula. Ovary, 397. Flowers of any species. 



sinensis. Glandular hairs, 97. Leaf-stalks. Fresh. 

 Protococcus viridis, 259. On damp bark or walls. Fresh. 

 Primus domestica (Plum). Structure of fruit, 423. Fruit. Fresh. 

 Pteris aquilina (Bracken-fern). Structure of stele, 172. Young leaf-stalks 



or slender rhizomes. Fresh, or in alcohol. 



cretica. Structure of root-apex, 224. Roots. Fresh, or in alcohol. 



Very commonly cultivated in pots ; and roots can be best obtained 



unbroken by turning the plant out of the pot containing it. 

 P-uccinia graminis (Rust-fungus), 330. Dry, or in alcohol. Found in 



summer on different kinds of cereals, and on Triticum repens (couch- 

 grass). 

 Pyrola (Winter-green). Embryo-sac, 401. Flowers. Fresh. Herbaceous 



perennials, various species of which can be easily cultivated on a 



shady border, in sandy peat. 

 Pyrus communis. Stone-cells in fruit, 65. Fresh fruit. 



Malus (Apple). Structure of fruit, 425. Fresh fruit. 

 Pythium de Baryanam. A parasitic and saprophytic fungus causing the 



disease known as "damping off". Obtained upon cress seedlings 



(q.v.), 321. 



Q. 



Quercus pedunculate (Oak). See Gall. 



Suber (Cork oak). Structure of cork, 187. Bottle cork. 



R. 



Ranunculus repens (Creeping Buttercup). Structure of roots, 168. Roots. 

 In alcohol. 

 Structure of vascular bundle, 121. Runners. In alcohol. 



Rhamnus Frangula (Buckthorn). Inter-protoplasmic union, 457. Secon- 

 dary cortex. Fresh. 



Rlwdodendron. Pollen, 391. Flowers. Fresh. (For substitutes, see Aza- 

 lea, Erica, Calluna.} 



Ribes rubrum (Red Currant). Structure and development of cork, 187. 

 Young and older stems. Fresh, or in alcohol. Best gathered in 

 July. 



Ricinus communis (Castor Oil). Aleurone grains, 33. Seeds. 



Stems of seedlings used for vascular bundles, as a substitute for 

 Aristolochia (q.v.), 136. 



Robinia Pseud-Acacia. Leaf-fall, 203. Treat as in ^Esculus. 



Old stems used for tyloses (tracheal plugs), 162. Fresh, or in 

 alcohol. 



Rosa semperflorens. Structure of prickles, 94. Young stems. Fresh. 

 Also leaves. Fresh. Most sp. of Rosa will do. 



Rose. Coloured cell-sap, 55. Petals. Fresh. 



