THE DISSEMINATION OF PARASITIC FUNGI AND 

 INTERNATIONAL LEGISLATION. 



BY 



E. J. BUTLER, M.B., F.L.S., 



Imperial Mycologist. ^ 



A FUNGUS is a minute plant, composed of a vegetative part (mycelium) 

 and seed-like reproductive bodies (spores). It may be disseminated by the 

 mycelmm or by spores, and in no other way. 



The mycelium is incapable of independent spread for any considerable 

 distance, except in rare cases : it is usually adherent to the substance on which 

 it grows, often immersed wholly or in part in it ; small fragments detached 

 perish quickly ; and larger pieces, which might preserve their vitality, fall 

 to the ground before long when carried into the air. Just as it is well known 

 that in the higher plants the vegetative body is less able to stand extremes of 

 heat and cold or dryness than the seeds, so also in the fungi the mycelium is 

 generally less resistant to such unfavourable conditions than the spores. 

 Laboratory w^orkers who are engaged in the cultivation of living fungi aie 

 familiar with this fact. Furthermore the fungi which cause disease in plants 

 are parasites and for the most part cannot long survive in their vegetative 

 condition (unlike the spores) unless able to obtain living food from the plants 

 on which they grow. 



Hence, dissemination over long distances in the mycelial condition only 

 occurs when the substance on which the fungus is growing is itself conveyed 

 from one place to another ; in the case of parasites such dissemination is prac- 

 tically confined to occasions when the plants^ on which they feed are moved, 

 though a few cases, such as facultative soil parasites, may travel with earth 



• Living plants are taken to include not only complete plants, but also cuttings, buds, 

 f*^ tubers, bulbs, seeds, and any other part that can survive detachment from the plant, even 

 CD (within limits) cut flowers and green leaves. Some parasitic fungi can also survive in a vege 

 tative and often quite long-lived condition on dead parts of plants. 



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