IQ 1 2] 



GA GER— INGROWING SPRO U TS 



517 



potato of fig. 4, the internal sprouts would often grow through the 

 skin and emerge at various points. 



The branches tuberized freely, and it was not uncommon to 

 find five or six, or even more, well formed, but pure white, tubers 

 of various sizes entirely within the old tuber. In some cases, as 

 in the right hand specimen of fig. 5, the branches were only imper- 

 fectly tuberized, and the tip retained its nutation curvature. Often, 

 as noted above, the young tubers, like the unswollen branches, had 

 pushed through the skin of the potato and, where exposed to the 

 air, had developed a characteristic brown epidermis (fig. 4). 



Fig. 5. — Dissected tubers of Solatium tuberosum, showing various stages of tuberi- 

 zation of branches of ingrown sprouts, both within and without the seed tuber (cf. 

 figs. 2 and 4) . 



In many instances there was every appearance of a reversal 

 of polarity of the sprout. This is clearly shown in fig. 6, which 

 illustrates two "eyes," the one at the left of a normal potato, the 



abnormal 



What 



appears 



former: roots occur at the distal end of the sprout, where we would 



terminal 



appear to have developed from the proximal end of the sprout, 

 Whether this is actually the case or not one hesitates to say. It 

 is possible that the entire shoot system, shown at the right in fig. 6, 

 may have developed from a sprout whose tip turned through 180 



