458 



Journal of Agricultural Research 



The relatively high percentage of ash in the sprout of the potato as 

 compared with that contained in the exhausted tuber is a matter of 

 interest. It will be seen, however, that considerable amounts of ash 

 still remain in the exhausted tuber after the growth of the sprouts is 

 complete, indicating the necessity of mineral matter for those changes 

 occurring in the tuber during the act of sprouting. Table VI gives the 

 percentage distribution of the several mineral constituents between the 

 sprouts and exhausted tubers, including the skin. 



Table VI. — Percentage dislribuiion of the mineral constituents of potatoes 



In Table VI it is observed that a large amount of the mineral material 

 remains unused in the exhausted tuber of the potato and that approxi- 

 mately only 15 per cent of the different mineral constituents have mi- 

 grated to the sprouts. 



CONCLUSIONS 



The most striking fact brought out thus far by these studies on the 

 translocation of the mineral matter of the seed and tuber during the 

 growth of the seedling is the retention of considerable amounts of the 

 mineral matter, varying from 46.66 per cent in the garden bean and 

 38.66 per cent in com to 50.33 per cent in the potato tuber in the cotyle- 

 dons and tuber, respectively. As indicated in the foregoing experi- 

 ments, this probably finds its explanation in the necessity for definite 

 amounts of the various mineral constituents to promote the katabolic 

 changes occurring in the cotyledon and tuber during sprouting. So far 

 as could be ascertained, there were no very striking differences in the 

 quantities of its several mineral constituents translocated and no marked 

 selective influences shown by the roots, stem, and leaves of the growing 

 seedling for any particular mineral reserve material contained in the seed 

 or tuber. Up to the present time, great difficulty has been experienced 

 in the selection of a suitable container in which to grow these seedlings. 

 This has proved a serious obstacle to this work. It is hoped, however, 

 that this difficulty may be finally overcome and better and more con- 

 stant results obtained through the use of pure paraffin containers. 



