144 DISKASK IN PI,A\TS. 



SO many cuttings "damp off," but that an)' are 

 raised at all under ordinary conditions. 



That worms bring buried spores to the surface 

 can hardly be doubted after Pasteur's experiments 

 with Anthrax, and the principle of Darwin's dis- 

 coveries 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 hone\' 

 dew (Ergot), or by sweet odours (Spermogonia, 

 Sclerotinia), the zoospores of Pythiuvi, Phytoph- 

 thora, 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 activel}- 

 brought about, and similarly with the amoebae of 

 Plasniodiophora in the soil. 



The shooting of ascospores into the air b}- 

 certain species of Peaisa, 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 dis- 

 tribution of their spores. But when we come to 



