10 



throw off diseases to which its more pampered brother 

 would succumb. Many generations of special treat- 

 ment have rendered the potato comparatively weak in 

 constitution, as is evidenced by its aptitude to succumb 

 to various kinds of disease which affect it very slightly 

 when growing in a state of nature. 



Necessity for the Production of New Varieties. 



Until within comparatively recent years the life of a 

 particular variety was much longer than is found in 

 the average of instances now. Before the outbreak of 

 the potato disease, in 1845, varieties were kept in culti- 

 vation longer than was profitable, but, as there was no 

 special disease to resist, the fact of their having become 

 enfeebled was not readily noticed. When the disease 

 appeared most of the varieties were without vigour to 

 resist it, and the devastation was correspondingly in- 

 tense. Greater attention has since been bestowed on 

 the cultivation of the potato, and all growers of ex- 

 perience realise that the profitable life of a variety is 

 short, and that it is necessary to obtain new varieties. 



Means of Obtaining New Varieties. 



New varieties, so far as they are suitable for market 

 purposes, can only be obtained from strains of the ori- 

 ginal stocks; fortunately, the original stocks develop 

 many different characteristics and features which are 

 very diversified in their nature. The diversity is so 

 strong that when by cross-fertilisation they are brought 

 together so as to form a new variety, many of the 



