105 



ing the first formed tuber. This cord shoots from the 

 opposite end to that which bears the first tuber, and 

 is, in fact, a narrow continuation of it. 



Second growth is caused by a temporary check in 

 the formation of the tuber, but some varieties are 

 much more liable to it than are others. When po- 

 tatoes are grown on the same soil and under the same 

 conditions for a number of years the potato loses 

 vigour, and very slight causes are sufficient to effect a 

 check in the formation. When conditions become 

 more favourable the formation continues, but instead 

 of the tuber thickening in the part already formed it 

 grows on at the end. The tendency to develop 

 second growth increases as the time from the intro- 

 duction of the variety increases, and often leads to its 

 being discarded. If a quantity of potatoes show great 

 variation in type, and a large number have acquired 

 second growth, it is probable that the stock is a 

 bad and weak one. However, if the season in which 

 they were grown was a dry one, it is possible that 

 other influences may have unduly affected them. If 

 a long drought causes the plants to stop growing for 

 a time after the tubers have commenced to grow, and 

 is followed by copious rain, after- growth may be ex- 

 pected, even in the case of vigorous varieties. With 

 this exception an ill-shaped sample should be regarded 

 suspiciously. 



Modern Varieties. 



Great attention has been paid during recent years 

 to the development of new varieties, consequently the 



