230 AGRICULTURE 



no doubt, like their predecessors, ultimately 

 to give way before newer varieties. 



New varieties of potatoes are all obtained 

 by raising seedlings, which are either got 

 by the indiscriminate sowing of the seed of 

 the berries, or are the result of the definite 

 crossing of distinct varieties. Most of the 

 seedlings are no improvement on their 

 parents ; but, by careful selection, a certain 

 proportion showing desirable features may 

 be separated out, and when these have been 

 vegetatively propagated in sufficient quantity 

 they are distributed through the ordinary 

 trade channels. 



Not only have certain varieties of potato 

 exceptional powers of disease resistance, but 

 the same is also true of other plants, such 

 as wheat ; Rivet or Cone, for instance, being 

 much more resistant to rust than others, 

 such as Michigan Bronze. From time to 

 time, also, varieties of turnip with marked 

 powers of resistance to the attack of finger- 

 and-toe are put on the market ; and similarly 

 in the case of gooseberries (resistance to 

 American Mildew), apples (resistance to 

 canker), etc. 



Many individuals and commercial firms 

 are engaged in this and other countries in 

 attempting to improve existing varieties of 



