8 ON THE GENERAL FEATURES OF FUNGI. 



exclude fi-om their special nidus. Other kinds ai-e apparently dis- 

 seminated by water, by the sap of plants, by the blood and excreta 

 of animals, birds, reptiles, or insects, and in yet other ways. 



The geogi-aphical distribution of Fungi is not determined by 

 precisely the same conditions which govern the distribntion of 

 other plants. To begin with, the Mycology of a gi-eat part of the 

 world is totally nnexplored. Only a few general remarks can be 

 hazarded on this head. The temperate and sub-tropical zones 

 ap]iear to be the most prolific in vai-iety and abundance of species. 

 Alany Fungi are found almost universally. Othei^ are restricted 

 to their zone. The least proportion are confined to special loca- 

 lities. ]!lIigrations seem to be going on. Parasites follow the 

 migration of their foster-plants. But not only this : independent 

 forms change their location. Tlie Fungi of North America are 

 more nearly akin to those of Europe than is the case with other 

 plants. In fact, America possesses most of the species inhabiting 

 Europe. Great Britain has generally the same Fungi as the north 

 of Europe, the peculiar species of countries being very few, My- 

 cological regions differ according to degrees of humidity and heat. 

 Forests are more prolific than open plains ; and there is a differ- 

 ence between forests of Conifera? and those of other trees, in the 

 Fungi inhabiting them. Some species confine themselves to 

 limited habitats, and the laws of their migration and diffusion are 

 yet unknown. 



