vi THE SPKEADING OF FOOD-PLANTS 75 



which were taken over to Europe seem to have been 

 practically all alike, but as soon as they began to 

 spread, all sorts of differences appeared. Some plants 

 were as spiny as or even spinier than the original, 

 but some had hardly any spines at all. Now, even 

 the camel, which is not particular, will not swallow 

 inouthfuls of spines, or at least if he does there are 

 apt to be unpleasant consequences, but both the 

 camel and other grazing animals will eat " prickly " 

 pear which is not very "prickly." In Tunis, in 

 Southern Spain, and elsewhere this was noticed, 

 and as in these places fodder is hard to get for the 

 animals, the forms with the fewest spines were 

 carefully picked out and grown in fields for the 

 farm beasts. 



In those parts of the United States where 

 fodder is equally hard to get, the farmers try to use 

 the prickly pear by first singeing off the spines 

 with a torch, and then giving the green joints to 

 their cattle. It would, of course, be much better 

 to grow only the spineless kinds, and the Bureau 

 of Plant Industry is now actually bringing back 

 from the Mediterranean the spineless varieties of 

 the prickly pear to try to grow them in the dry 

 parts of America. This is a very curious fact 

 the re-introduction of a native plant. The experts 

 are searching all over the world, wherever the 

 plant has been introduced, for useful varieties 



