it seems at the same time probable from Baron Humboldt's extensive collections, and from what we know of the vegetation of the West India islands, that in equinoctial America, in tracts including a considerable portion of high land, the ratio of Dicotyledones to Monocotyledones is at least that of 11 to 2, or perhaps nearly 6 to 1. Whether this or a somewhat diminished proportion of Dicotyledones exists also in similar regions of other equinoctial countries, we have not yet sufficient materials for determining.
Upon the whole, however, it would seem from the facts of which we are already in possession, that the proportions of the two primary divisions of phænogamous plants vary considerably even within the tropics, from circumstances connected certainly in some degree with temperature. But there are facts also which render it probable, that these proportions are not solely dependent on climate. Thus the proportion of the Congo collection, which is also that of the equinoctial part of New Holland, is found to exist both in North and South Africa, as well as in Van Diemen's Island, and in the south of Europe.
It is true indeed that from about 45° as far as to 60°, or perhaps even to 65° N. lat. there appears to be a gradual diminution in the relative number of Dicotyledones; but it by no means follows that in still higher latitudes a further reduction of this primary division takes place. On the contrary, it seems probable from Chevalier Giesecke's list of the plants of the west coast of Greenland,[1] on different parts of which, from lat. 60° to 72°, he resided several years, that the relative numbers of the two primary divisions of phænogamous plants are inverted on the more northern parts of the coast;[2] Dicotyledones being to Monocotyledones, in the list referred to, as about 4 to 1,
- ↑ Article "Greenland," in Brewster's 'Edinburgh Encyclopædia.'
- ↑ That some change of this kind takes place on that coast might perhaps have been conjectured from a passage in Hans Egede's 'Description of Greenland,' where it is stated, that althongh from lat. 60° to 65° there is a considerable proportion of good meadow land, yet in the more northern parts, "the inhabitants cannot gather grass enough to put in their shoes, to keep their feet warm, but are obliged to buy it from the southern parts." (English Translation, pp. 44 and 47.)
