1883.] Means of Plant Dispersion. 1033 
the chief carriers of produce, with which seeds are more or less 
mixed, may also be noticed. That plants migrate along their 
road-beds, where they find a natural highway, is evident from the 
manner in which the plants of different regions are found to be 
mingled, when capable of this migration, going along step by 
step. But they too travel by rail, like members of the other 
kingdom of nature, and the diligent collector will from time to 
time be rewarded with a species new to his locality, which by its 
sudden appearance and isolation will not easily be accounted for 
in any other way. 
In relation to what has been said, it is a matter of interest to 
compare plants and animals with reference to their distribution, 
and see which has the advantage in the struggle for existence. 
It may be thought that the free-moving animal excels the fixed 
plant in this respect. But a study of the whole life of each 
shows that many species of plants have the advantage over ani- 
mals. If we compare the faunas and floras of the different con- 
tinents, or of wide regions of the same continent, the number of 
plants of wide distribution much exceeds the number of animals. 
It is especially true of cryptogamous plants, and in the northern 
Parts of the northern continents. Of the 2928 species of plants 
given in Gray’s Manual of Botany, 2668 are indigenous, and 676 
indigenous species are common to Europe, or twenty-five per 
cent. Of the mosses, including Hepatice, 502 are enumerated, 
320 of which are found in Europe, or sixty-three per cent. Of 
the vascular Cryptogams, thirty-five of the seventy-five are com- 
Mon to the two continents, or about fifty per cent.’ Some 
changes would have to be made in these figures if a comparison 
based on later discoveries were instituted, but not materially 
affecting the principle of distribution involved. This comparison 
is made between land and fresh-water plants and animals dwell- 
ing under the same conditions. It may be different with marine 
plants and animals. This advantage of the plant is doubtless in 
a great part attributable to its greater capability of enduring 
changes while in the act of migration.- It is of a lower order of 
life, and less sensitive to change in some stages of its existence. 
Mountains, often of no great height, seas, often of no great width, 
are insuperable barriers to the migration of animals; they perish 
by cold, or hunger, or drowning, in their attempts to cross them. 
: Gray’s Manual of Botany with Mosses, 1856. Introduction. 
