RELATIONS OF ANIMALS AND PLANTS 135 



generally provided with hooks with which they 

 entangle themselves in the feathers or hair of passing 

 creatures ; others are produced in a fleshy pulp, 

 which is eaten, and some at any rate of the seeds 

 pass unharmed through the intestines of bird or 

 mammal, or stick to its exterior until they are 

 deposited perhaps at a distance from the parent 

 plant. Numberless examples of seeds and seed- 

 vessels armed with hooks and spines could be quoted 

 from the flora of the Great Palaearctic Desert, especi- 

 ally from the annuals ; it is a common thing to 

 find such " burrs " in large numbers in the coats 

 of sheep, jackals, and even such smooth-haired 

 animals as gazelles and jerboas. Fleshy fruits are 

 not common in deserts, and many of those which 

 occur are so bitter or nauseating, or in other ways 

 unattractive, that they are shunned by the fauna. 

 Schimper states that jackals disperse the seeds of 

 CitruUus, presumably after biting the fruit, but I do 

 not think this is a common occurrence. The fruits 

 of many members of the Cactus family are sweet 

 and fleshy, though protected by spines. I have 

 already quoted Tuomey's remarks about the fruit 

 of Cereus giganteus and the birds which are attracted 

 to it ; Spalding adds that squirrels fatten on the 

 fruit of Echinocactus ; one is probably justified in 

 concluding that the seeds of the Cactus family are 

 largely spread by animals and birds. The date- 

 palm {Phoenix dactylifera) is entitled to a place on 

 the Hst, though palms which produce fruit edible to 

 man do not exist wild. 



Dates in Mesopotamia are eaten greedily by 



