12 



TRANSLOCATION OF PLANT FOOD IN WHEAT SEEDLINGS. 



assumed a horizontal position, and it would seem that further absorp- 

 tion of salts from the seeds was an impossibility, indicating that the 

 small amounts of salts and of nitrogen left in the seed coating or bran 

 are the most difficult of absorption. 



EXAMINATION OF THE ENTIRE PLANT. 



Table 1 shows the amount of nitrogen, phosphoric acid, and potash 

 in the whole plant, including the axes and the residual seed, these 

 figures being obtained on seedlings grown in distilled water, after 

 being thoroughly steeped in many changes of water. The figures are 

 expressed as the percentage of the original amounts, namely, seeds 

 100 of which contained 0.051 gram of nitrogen, 0.0328 gram of phos- 

 phoric acid, and 0.0194 gram of potash, and which weighed 3.50 

 grams. 



TABLE 1. Percentage amounts of nitrogen, phosphoric add, and potash in the entire 

 plant (plumule-\-radicle-\-residual seed), based on amounts in original seed. 



[Grown in distilled water after steeping.] 



This table shows that even when grown in water the entire plant 

 (residual seed plus the axes) takes up an appreciable amount of potash 

 and nitrogen, but hardly any phosphoric acid, during the early stages 

 of growth. It will be noticed that, although the seedlings were grown 

 in water, the amounts of nitrogen and potash found in the plant at 

 the end of 12 days were greater by one-fifth and over one- third, 

 respectively, than those found in the original seed. This is due to 

 the fact that both germinated and ungerminated seeds lost through 

 leaching a certain amount of the salts which they contained, and 

 that some of these salts were absorbed by the seedlings, as before 

 explained. Experiments have demonstrated that much the greater 

 portion of soluble plant food is removed by the first few hours of 

 steeping, but that some inorganic constituents continue to be pro- 

 duced by cleavage from organic compounds, even after several 

 changes in steep water have been made. It is seen, therefore, that 

 it is almost impossible to eliminate the slight error due to the 

 excretion of salts from the seeds. 



