INTRODUCTION TO SOCIOLOGY 2 29
One observes two modes of occurrence of the species upon the globe: first, either they abound in one locality, the individuals being grouped near each other, and forming the social species; or else, secondly, they predominate in a whole country; then one calls them frequents or scattered. The agglomeration of the individuals of the same species belongs to the constitution of the species itself and to the conditions of each local station.
There are some plants which injure very much their neigh- bors: (a) by the rapidity of their growth (willow and other white wood); () by the length of their stems (Gramineae and perennial cypress); (c) by the shade of their foliage (beech, fir). These are anti-social toward each other. Other species have an extraordinary abundance of seed, which the wind is not able easily to disperse, or which germinate rapidly and continuously (spinach, mercurialis, wild poppy) . Finally certain plants are provided with means of multiplication very favorable for sub- divisions or ramifications (Ranunculus aquaticus, strawberry plants). Their constitution in each case renders them naturally social.
As to the conditions of each local station, the presence of matter favorable to the vegetation of a certain species ought to multiply it ; and, on the contrary, the absence of such other matter necessary to the life of other species ought to exclude the latter (Leguminosae in the calcareous soils, briar in the sterile places, nivale plants on the summit of mountains). The climate, on the contrary, has no influence upon the sociality of plants. A species remains social up to the limit where it is able to live. At the north there are some forests of a certain species up to the geographic limit of the species itself. Going from the center of France toward the south one sees, following one another, the social species of this zone in a state of decided agglomeration (cistus, turpentine trees, lavender).
In general, the more there are in a country of different species which are able to dispute the territory over each station, the less there are of the agglomerated species. Thus in equatorial coun- tries, the vegetation being more rich in species than in the northern regions, there are fewer social species. Contrary to this, the uniformity of the human species is favorable to sociality.
