Waltershausen estimates the annual consumption of that mineral for this single purpose at 850,000 centner, or more than forty thousand tons. The price of sulphur has risen in about the same proportion as that of the wine.--Waltershausen, Ueber den Sicilianischen Ackerbau, pp. 19, 20.] All the operations of rural husbandry are destructive to spontaneous vegetation by the voluntary substitution of domestic for wild plants, and, as we have seen, the armies of the colonist are attended by troops of irregular and unrecognized camp-followers, which soon establish and propagate themselves over the new conquests. These unbidden and hungry guests--the gipsies of the vegetable world--often have great aptitude for accommodation and acclimation, and sometimes even crowd out the native growth to make room for themselves. The botanist Latham informs us that indigenous flowering plants, once abundant on the North-Western prairies, have been so nearly extirpated by the inroads of half-wild vegetables which have come in the train of the Eastern immigrant, that there is reason to fear that, in a few years, his herbarium will constitute the only evidence of their former existence. [Footnote: Report of Commissioner of Agriculture of the United States for 1870.] There are plants--themselves perhaps sometimes stragglers from their proper habitat--which are found only in small numbers and in few localities. These are eagerly sought by the botanist, and some such species are believed to be on the very verge of extinction, from the zeal of collectors. ANIMAL LIFE AS A GEOLOGICAL AND GEOGRAPHICAL AGENCY.