INDEX 
Oil, 18, 19. 
Oil, essential, 21. 
Oil, extraction, 18, 19. 
Oil, testing seeds for, 19, 20. 
Onion, bulb of, 59. 
Onion leaf, section of, *61. 
Onion, structure of, 84, 85. 
Onion, tests for food-materials in, 
85. 
Onoclea, *286. 
Odgonia, *226, *229, *232. 
Odsphere, *232. 
Opposite, 51, *52, 106, #107, #108, 
*109. 
Oranges, 329, 330. 
Orbicular, App. I, #355. 
Orchid, aérial roots of an, 30. 
Organs, essential, *148. 
Organs, vegetative, 24, 25. 
Ornamental plants, 342. 
Oscillatoria, type study, 216~218*. 
Osmosis, 45-47*, 
Osmosis in an egg, 45, *46. 
Osmosis in root-hairs, *46, 47. 
Ovary, *154-156. 
Ovate, App. I, *355. 
Ovoid, egg-shaped, like the spores 
in Fig. 182. 
Ovule, 153, *154. 
Ovule, spruce, fertilized, *302. 
Ovule, structure of, *166. 
Oxalis leaf, development of, *94. 
Oxidation, 10. : 
Oxygen, 10, 1386. 
Oxygen making, 137. 
‘ 
Palisade-cells, *128. 
Palmate, 100, *102, 103. 
Pampas region, 204. 
Panicle, *198, App. I, *359, 
3875 
Pansy, leaf-like stipules of, *101. 
Papilionaceous corolla, *150. 
Papillz on stigma of a lily, *165. 
Parasites, 32, *33. 
Parasitic roots, 382, #33. 
Parietal placenta, *155. 
Parsnip root, study of, 37, 38. 
Pea seed, *8, 12, *13. 
Pea seedling, mutilated, 12, *13. 
Pear buds, *91. 
Pear fruit spurs, *91. 
Pedicel, App. I, *357. 
Peduncle, App. I, 357. 
Peg of squash seedling, 23, 24. 
Peltate, App. I, #356. 
Pepo, 188. 
Perennial, 39, 54. 
Perianth, *148. 
Pericarp, 187. 
Perigynous, *156. 
Perisperm, 13. 
Petal, 148, 146, 148, 
Petiole, 98. 
Phanerogams, 209, 211. 
Phanerogams, classes of, 211, 
Phosphorus, 135. 
Phytopthora, #249. 
Pine, seedling, *28. 
Pinnz, leaflets of a pinnately com- 
pound leaf, *103. 
Pinnate, *98, *99, *103. 
Pinnules, *244, 245. 
Pistil, 148-145, 147, *148, *161, 
*158, 154. 
Pistil, parts of, *153. 
Pitcher-plant, *118, 120. 
Pith, *65, 66, 67, *68, *70, *71, *72. 
Placenta, 154, *155, 
Plant breeding, 309-323. 
Plant societies, 113, 114. 
