winged insects, and sometimes that of the birds which are attracted by the perfume of the honey vessels. Such is their number and variety that, to mention only a limited district, the entire life of a painter would be too short for the delineation of all the magnificent Orchideæ which adorn the recesses of the deep valleys of the Andes of Peru.
The Casuarina form[22], leafless, like almost all species of Cactus, consists of trees with branches resembling the stalks of our Equisetums. It is found only in the islands of the Pacific and in India, but traces of the same singular rather than beautiful type are seen in other parts of the world. Plumier's Equisetum altissimum, Forskäl's Ephedra aphylla from the north of Africa, the Peruvian Colletias, and the Siberian Calligonum pallasia, are nearly allied to the Casuarina form.
As the Banana form shews the greatest expansion, so the greatest contraction of the leaf-vessels is shewn in Casuarinas, and in the form of Needle trees[23] (Coniferæ). Pines, Thuias, and Cypresses, belong to this form, which prevails in northern regions, and is comparatively rare within the tropics: in Dammara and Salisburia the leaves, though they may still be termed needle-shaped, are broader. In the colder latitudes the never-failing verdure of this form of trees cheers the desolate winter landscape, and tells to the inhabitants of those regions that when snow and ice cover the ground the inward life of plants, like the Promethean fire, is never extinct upon our planet.
Like mosses and lichens in our latitudes, and like orchideæ in the tropical zone, plants of the Pothos form[24] clothe
