THE DISPERSION OF SEEDS AND SPORES. 119 



itself in length. The writer has seen a specimen of 

 a fruit very similar to this but much larger, the 

 prongs being six or eight inches in length. The 

 specimen was said to have been obtained from 

 Australian wool. In some parts of the south of 

 Scotland this fruit is frequently preserved as a 

 household curiosity, and is known locally as the 

 " Devil's horns." The snake-fang seeds from the 

 West Indies, shaped like almonds, but larger, have 

 two recurved hooks at one end, and are occasionally 

 seen in museums. The mericarp of Pavonia spinifex,. 

 a malvaceous plant, has three diverging prongs beset 

 along their edges with backward-pointing barbs. 

 Triu7nfetta is a genus of tropical weeds with bur- 

 like fruits similar to those of the bedstraw. Acceiia 

 procumbens has several slender spines barbed at 

 their extremities like arrows. The seed of Villarsiaf 

 an aquatic plant, is fringed with ciliated processes 

 apparently intended to catch on to a passing animal. 

 Hooked appendages might prove a disadvantage 

 rather than a benefit if there w^as any possibility of 

 the fruit becoming detached from the mother-plant 

 before the seeds were ripe. The fruit is therefore 

 firmly attached to the mother plant, and only at 

 maturity is the connection so weakened as to admit 

 of easy separation. Moreover, the sharp points of 

 the hooks are seldom exposed until the fruit is- 

 perfectly I'ipe. As long as they are unripe, the 

 fruits of Geuin, Galium, etc., have little or no adhesive 

 power. In Geuin and Agrimonia the hooked pro- 

 cesses are at first vertical ; but as the fruit ripens 

 they spread out and bend downwards, so that the 

 booklets come to be exposed. The agrimony fruit 

 is at first erect, but when ripened is inverted by 

 the bending round of the peduncle. If the fruit be- 

 preserved for some time, the booklets are seen to 

 come together again as if for the purpose of 

 tightening their grasp. During the time the seeds 

 of the carrot are ripening, the rays of the umbel 

 are gathered close together, the inflorescence forming^ 



