OCR Text |
Show SUMMARY OF THE CO TENTS. 465 equal; whilst we know that certain well-explored districts in Europe ha>e more than three times as many insects as phamogamous plants 303-306 Considerations on the probable proportion which the number of known phrenogamous plants bears to the entire number existing on the surface of the globe . . . . . . . . 306-310 The different forms of plants successively notieed. Physiognomy of plants treated in a threefold manner; viz. as to the absolute diversity of form , their local predominance in comparison with the entire number of pecies in different phrenogamous Floras, and their geographical climatic distribution . 312-363 Greatest extension in height or of the longitudinal axis in arborescent vegetation: examples of 235 to 245 English feet in Pinus lambertiana. and P. douglasii; of 266 English feet in P. strobus; of 298 and 300 English feet in Sequoia gigantea and Pinus trigona. All these examples are from the north-west part of the New Continent. Araucaria excelsa of Norfolk Island only attains, according to wellassured measurements; 203 to 223 English feet; and the Mountain Palm ofihe Cordilleras, Ceroxylon andicola, 192 English feet 338-340 These gigantic vegetable forms contrasted with the stem of two inches high of a willow-tree stunted by cold of latitude or of mountain elevation; and still more remarkably with a phrenogamous plant, Tristicha hypnoides, which, when fully developed in the plains of a tropical country, is only a quarter of an English inch in height 341 Bursting forth of blossoms from the rough bark of the Crescentia cujete, the Gustavia augusta, and the roots of the Cacao tree. The largest flowers, Raffi.esia arnoldi, Aristolochia cordata, Magnolia, Helianthus annuus, Victoria regina, Euryale amazonica, &c. 364-365 The different forms of plants determine the character of the landscape as dependent on vegetation in different zones. Physiognomic classification or division into groups according to external "fancies" or aspect, entirely different in its principles from the classification according to the system of natural families. The study of the physiognomy of plants is based principally on what are called the vegetative organs, or those on which the preservation of the individual depends; Rystematic . botany grounds the arrangement of natural families on a consideration of the reproductive organs, or those on which the preservation of the species depends 367-371 On the Structure and Mode of Action of Volcanos in the dijferent Parts of the Earth-p. 373 to p. 394. Influence of journeys in distant countries on the generalization of |