That worms bring buried spores to the surface can hardly be doubted after Pasteur's experiments with Anthrax, and the principle of Darwin's discoveries of the important bearing of the habits of earthworms on this subject, and that the soil attached to the feet of ducks and other birds teems with small seeds, applies to fungi also. Wind is also responsible for distributing fungus-spores over wide areas, as may be easily proved by fixing a glass slide smeared with glycerine in the course of a breeze passing over an infected area. But although the fungi are, generally speaking, passive in regard to their distribution, such is by no means always the case. Apart from the fact that some forms attract insects by means of honey dew (Ergot), or by sweet odours (Spermogonia, _Sclerotinia_), the zoospores of _Pythium_, _Phytophthora_, etc., are motile, and although they cannot move far in the films of water in which they travel, nevertheless in a wet potato field, with the wind flapping the leaves one against the other, some dissemination of importance must be actively brought about, and similarly with the amoebae of _Plasmodiophora_ in the soil. The shooting of ascospores into the air by certain species of _Peziza_, from the discs of which the spores may be seen to puff out in clouds, affords further evidence that fungi cannot be regarded as entirely passive in respect to distribution of their spores. But when we come to certain of the soil fungi--_e.g._ _Agaricus melleus_, _Dematophora_, etc.--the active creeping forward by growth in the soil of their rhizomorphs and mycelial strands afford examples of active spreading of considerable importance in the vineyard and forest, since they pass from root to root and from tree to tree and may infect the entire area in course of time. Not the least significant mode of dissemination is that by which what I have termed "lurking parasites" are spread: such are fungi which attach themselves to the seeds, fruits, tubers, etc., of other plants and so obtain all the advantages of being carried and sown with the latter--_e.g._ Ustilagineae and Uredineae which adhere to grain, _Verticillium_, _Nectria_, etc., in potatoes and other plants. The spread of diseases due to animals, especially insects, is of course more active, in consequence of the motility of the distributing agents. This is most marked in the winged species, of which locusts, beetles, moths and butterflies, flies and wasps furnish well-known examples; and is not inconsiderable in the case of wingless and merely creeping species. It is noteworthy that many forms wingless in the parasitic stage are winged at certain periods, _e.g._ the females of _Phylloxera_. That man also spreads insect pests is well known and acted upon, as witness the phylloxera laws--which, however, it is to be feared too often only illustrate once more the adage concerning the shutting of the stable door after the horse has gone.