156 DISKASl-: IN PLANTS. 



also been shown that hybrids can be obtained 

 which are resistant. 



But the most curious point of all is that 

 Phylloxej'a was itself a native of /America, and 

 came thence to Europe. It had played its part 

 with certain fungi in ruining all the attempts to 

 introduce the European vine into America many 

 years ago. A recent authority on the evolution 

 of American fruits writes as follows : 



" All the most amenable types of grapes had 

 long since perished in the struggle for existence, 

 and the types which now persist are necessarily 

 those which are, from their very make-up or con- 

 stitution, almost immune from injury, or are least 

 liable to attack . . . the Phylloxera finds tough 

 rations on the hard, cord-like roots of any of our 

 eastern species of grapes. But an unnaturalised 

 and unsophisticated foreigner, being unused to the 

 enemy and undefended, falls a ready victim ; or if 

 the enemy is transported to a foreign country the 

 same thing occurs." 



Further proof that it is in the " constitution " of 

 the European vine that the want of resistance to 

 Phylloxera resides, is furnished by the fact that in 

 California and the Pacific states the European 

 vine was introduced with more success, but is 

 now suffering badly because Phylloxera has 

 spread there also. It must not be overlooked, 

 however, that we are as yet very ignorant of all 

 that is implied in the word " constitution " as used 

 above. 



If we enquire further why the Phylloxera 



