INDEX 



597 



Disjunct area (range), i88, 206, 210 

 Dispersal (of plants), 5, 97-127, 207 

 — , agents of, 97-127 



— in air, 99-106, 163 



— by air currents, 99, loi 

 travel, 1 19-20 



Dispersal of Algae, 106, 117, 510, 514 



— by animals, iii, 112, 113, 114-18, 



307 

 — , barriers to, 103, iii, 120, 125, 126 



— by birds, 109, 1 12-15, 117, 163, 420 

 — , centre of, 207 



— by growth, 121, 122, 123 



— by human agency. 1 18-21 

 — , ice and, 100, 106, 107, 109 

 — , intercontinental, 21 



— of marine Algae, 106, 514 

 — , means of, 98 



— , mechanical, 121, 122, 123, 124, 125 



— mechanisms, 99-103, 104, 105, 106- 



10, 113, 114-18, 121, 122, 123, 

 124-5 



— of seeds and fruits, 15, 69, 97-125 



— by water and ice, 106-1 1, 293, 468 



wind, 98, 99-106, 293, 434, 452 



Displacement hypothesis, 165 

 Disseminules, 97—8, 219, 374, 500, 510, 

 — , wastage of, 98-125 [551 



— , wind dispersal of, 99-103, 104, 105 

 Distribution (range, see also Area), 4, 14, 



154. 157. 158, 182-4, 186, 189 

 — , basic elements of, 212 



— of Conifers, 345-6 



— of crops, 6, 215-54 

 — , disease and, 250-1 



— , factors determining, 154, 563 



— , geographical, 8, 154-252, 572 



— , historical aspects of, 8 



— , in depth, of Algae, 39, 48s, 486, 487, 



488, 512 

 — , limiting factors of, 75, 565 

 — , modern, foundations of, 5, 154-81 

 — , natural, types and areas of, 6, 182— 



— pattern, 72, 177, 215 [214 



— of plant diseases, 248, 250-2 



— of weeds, 6, 248-53 

 Distributional and ecological aspects, 23 

 Distributions (ranges), types of, 183- 

 Divides, 544 [197 

 Dobzhansky, T., 579 



Doctrine of signatures, 262 

 Dodder, see Ciiscuta and C. epilinum 

 Dogwood, see Cornus and C. swiguineo 

 Dominance, 28, 329-34, 351, 468, 565 



— in deciduous forest, 337, 341 

 — , general consideration of, 329 

 — , mixed, 247, 428 



Dominants, 65, 325, 329-34, 34°, 347. 



348, 353, 354, 357, 37^, 383, 385, 



393, 400, 409, 428, 448, 463, 495, 

 516, 554, 565 



Dominants, arctic scrub, 392, 393 



— , Conifers as, 65-6, 343-50 



— , Cyperaceae as, 333, 443, 505 



— , Gramineae as, 360-4, 443-6 



— , hydrosere, 372 



— , Leguminosae as, 441 



— , Phaeophyceae as, 532, 533, 534-8 



— , Popidus spp. as, 343 



— , progressive change in, 323-4, 464 



— , secondary forest, 466 



— , semi-desert plants as, 365-6, 448 



— , taiga, 347, 348 



— , thorn-woodland, 442 



— , tundra, 383-6, 387, 389 



Dormancy, seed, 452 



Dormant bud, 425 



Dorstenia (Flat-fig), 124 



Doubling of flowers, 218 



Douglas Fir, see Pseitdotsuga taxifolia 



Drabble, H., 311 



Drepanoclodus, 503 



Drift-wood, dispersal by, 109 



Drimys zvinteri, 342 



Drip-tip, 428 



Drooping Ladies'-tresses, see Spir- 



anthes romanzoffiana 

 Drosera (Sundew), 91, 196, 373 



— sect, erythrorhiza, 196, 197 

 Drought-enduring plants, 78, 450-2 



— resistance, 10-12, 78, 82, 450-2, 564 

 in Algae, 526, 534 



, survival by, 78, 452 



Drude, O., 22, 471 



Drug, anti-malarial, 264 



Drugs, 3, 262-5, 267 



— , medicinal \alue of, 262—3 



Drumlins, 545 



Drummond, M., 95 



Dry tundra, 385, 386, 389, 392 



Dry-weight of crops, 229 



Dryos (Avens), 386, 392, 395, 397 



D. integrifolia agg. (Arctic Avens), 



396, 397, 398 

 D. octopetala s.l. (Mountam Avens), 



Dr\'ing oils, 235, 265 [173, 396 



Drynaria, 433 



Dryoptcris (Shield-fern), 60, 61 



Dii Rietz, G. E., xviii, 164, 167 



Duckweeds, see Lemna 



Ditdresnaya, 528 



Dulse, 259 



Dimaliella salina, 502 



Dunes (see also Sand-dunes), stabiliza- 

 tion of, 328, 366, 458, 548, 555, 566 



— , migration rate of, 548 



Dunn, L. C, 579 



Diirvillea antarctica, 535 



Dust seed, lor, 434 



Dutch Elm disease, 280, 306 



Dwarf Birch, see Betula nana agg. 



pine, Siberian, see Pinus putnila 



