Page:The Journal of Indian Botany, Volume III.djvu/49



The Mycological flora of such a large portion of the world remains unexplored that it is at present impossible to give a general view of the geographical distribution of fungi ; even in some of the civilized countries, the phanerogamic flora of which has been fully worked out, little has been done towards the collection and publication of lists of fungi ; the most we could at present is to compare the collection of one country with that of another and to note the difference and agreements. Such a comparison is useful as we learn how much there is to be known.

In case of fungi it so happens that species which were at one time very common gradually become somewhat rare and rare until they disappear altogether. The late illustrious Fries said “ The fact must not be lost sight of that some species of fungi which have formerly been common in certain localities, may become within our life time more and more scarce and even altogether cease to grow there. The cause of this doubtless is the occurrence of some change in the physical constitution of a locality, such as that resulting from the destruction of a forest, or from the drainage by ditches and cut-tings of more or less extensive swamps, or from the cultivation of the soil.”

In case of Polyporaceae it will be seen that the geographical limits of species are not so well marked and definite as in those of phanerogamous plants. When climatic conditions regarding temperature, rain-fall, humidity, etc., are analogous, it is astonishing to find the repetition of the species in very distant parts of the globe. But it is usually found that tropical countries abounding in virgin forests form the special abode of Polipori, which grow luxuriantly under the shade affording perpetual moisture and heat. Some species are practically cosmopolitan in their range, for instance, Fomes leucophaeus, which was already reported from the North temperate. South