DISPERSAL BY ANIMALS. 



873 



being eaten. Rogeria and Fedaliutn, mentioned on p. 875, also belong to this 

 family. 



In other plants it is the fruit-stalk instead of the style which is transformed 

 into a claw-like structure. In Cyclamen Europceum, for instance, the fruit-stalk 

 undei'goes spiral torsion and contraction. Formerly it was supposed that the object 

 of this curious phenomenon was to draw the fruits into the earth, where the seeds 

 would be favourably situated for germination. But this idea does not correspond 

 to actual fact. The green capsules are drawn underground in the late autumn 



Fig. 478.— Fruits with hooks. 



I MarmUum mdgare. 2 Medicago agrestis. = Rumex nepalensis. •• Scorpiunts sulcata. » Agrimonia odorata. " Orlaya 

 grandijiora. ' Pteranthus echinatus. « Rochelia Persica. » Onobrychis mquidentata. i» Trium/etta Plumieri. " Hooked 

 bristles on the fruit of Trium/etta Plumieri magnified. " Medicago radiata. is Xanthium spinosum. » Ceratoccphalus 

 falcatus. 15 Geum itrbanum. is A single fallen fruit of Gemn urbanum. 17 Lappa major. 



when the seeds are still unripe. They pass the winter in the earth, and do not 

 attain to complete maturity until the following summer. The desiccation and 

 severance of the twisted fruit-stalk then has the effect of pulling the fruit out of 

 the ground again, the lower portion of the stalk rots, and the part which is left 

 forms a claw surmounting the capsule. The latter, which is still full of seeds, lies 

 loose on the ground, and adheres to the foot of any animal that treads on it. The 

 manner in which these seeds are besides dispersed by ants has already been referred 

 to on p. 866. 



