Sft6 iKDi:i. 



soils, and others will not, 332 — aphyllous, office of leaves per 

 formed in, by the rind and epidermis, 40. 



Plumule, 22— derives its nourishment partly from the cotyledons and 

 partly through the agency of the rt ot, 22. 



Plurging of petted plants, 273. 



Poisonous substances fatal to man prove equally so to plants, 11, 



Poisons, alkaline, their destructive effects, 18 — metallic, destructive 

 to plants, 18. 



Pollen, agents which affect its fertilising powers, 11 1 — deficiency of, 

 a cause of sterility in seeds, 171. 



Potash, employed to promote germination, 166 — as a component of 

 manures, 335, 338. 



Potato, tubers of, early varieties, their appropriation of nutritive 

 matter, 173 — means of obtaining improved varieties oi, 308 — 

 unequal periods of its maturity from different eyes, 189. 



Potatoes, disease of, curl in the leaves of^ 73 — propagation o^ from 

 eyes, 186. 



Pots for plants, their drainage, 119 — double, for plants, 274 — neces- 

 sity of their being proportioned to the size of the plants, 277. 



Potting, 267 — objects attained by, 267 — cases in which it may bo 

 advantageously dispensed with, 268. 



Preservation of races by seed, 296. 



Pricking out seedlings, 268. 



Principles upon which the operations of horticulture essentially 

 depend, 101. 



Productiveness, 64. 



Propagation by budding and grafting, only successful within certain 

 degrees of affinity, 222 — its objects, 224, 228 — its rationale ex- 

 plained, 199, 226 — by cuttings, 195 — by knaurs, 189 — by layers 

 and suckers, 207 — by leaves, 189 — by eyes, 184 — by eyes and 

 cuttings, difference o^ from that by budding and grafting, 211 

 — by roots, depends on the formation of adventitious buds, 20. 



Protection afforded by walls, 266. 



Pruning, 239 — its objects, 239 — its effects, 248 — seasons for, 247 — of 

 transplanted trees, 248 — of roots, 249. 



R. 



Baces of plants, means of their preservation by seeds, 297 — meani 



of fixing their habits, 297 — accidental alterations in, 307. 



