THE DISPERSION OF SEEDS AND SI'ORES. 103 



Bafflesia, Stapelia, and other carri<iii-flowers, have 

 unpleasant odours certainly meant to be attractive. 

 It seems almost certain that some fungi do attract 

 insects, but for what end it is impossible, in the 

 present state of our knowledge, to say. The spores 

 of many leaf-parasites are beset with projecting 

 points. Echinate spores also occur in the truffle 

 (Tuber), and on the fungus which infests the colt's- 

 foot (Tussilago). A tuberculated surface is especially 

 characteristic of the Minter-sj)ores of such fungus- 

 parasites as Melavipsora hetulina, M. pojoidina, etc. 

 These tuberculations much resemble those observed 

 on the pollen-grains of Campanula, the hollyhock 

 {AWuva rosea), the melon (Cucumis Melo'^, and many 

 composites. In the case of pollen-grains, a tubercu- 

 lated surface serves to fasten them to the hairs of 

 insects or to the stigmatic papillae. It requires no 

 great stretch of imagination to suppose that the 

 intention is similar in these tuberculated spores. 

 Whether insects aid in their dispersion or not, the 

 projections will at least be of service in assisting 

 them to cling to the plant on which they are 

 destined to germinate and take up their abode. 



Belt, in his work on the Natural History of 

 Nicaragua, refers to an ant Avhich cultivates a 

 fungus for its own use in a leaf-mould Avhicli it 

 procures by sti'ipping off leaves from fruit-trees. 

 In the process of storing up grass-seeds, the har- 

 vesting ant may also occasionally assist in their 

 dispersion. In Natal, after every visitation of a 

 locust-swarm, farmers have remarked the appear- 

 ance of certain injurious weeds. From several small 

 pellets of locust-dung sent home to him, Darwin 

 succeeded in raising seven plants of various kinds. 

 The transport of seeds by insect-swarms is therefore 

 possible ; and, as they are often blown great distances 

 out to sea, by this means continental plants may 

 frequently be introduced into oceanic islands. 



7. Dispersion by Birds. — Humming-birds in Ameri- 

 ca, sun-birds in Africa and India, the brush-tongued 



