INORGANIC CONSTITUENTS. 9 



Besides growing the seedlings in water, as a control, they were 

 also grown in the following culture media: 



{a) Nitrate as sodium nitrate (NaNOg) (50 to 150 parts per mil- 

 lion) . 



(Jb) Potash as potassium sulphate (KgSO^) (50 to 150 parts per 

 million) . 



(c) Potash as potassium chlorid (KCl) (50 to 150 parts per mil- 

 lion) . 



id) Phosphoric acid as sodium phosphate (NagHPO^) (64 to 150 

 parts per million) . 



{e) Complete — 



Nitrate (NO3), 50 parts per million. 

 Potash (K2O), 50 parts per million. 

 Phosphoric acid (P2O5), 50 parts per million. 



The plants were grown for 2 weeks, at room temperature, gen- 

 erally during the winter and spring months, care being taken to grow 

 control plants in distilled water. In about 24 hours the embryo 

 could be seen breaking through the bran coating, and in about 48 hours 

 the plumule and radicle were large enough to be removed from the 

 mother seed. The axes were removed from 100 to 200 seeds every few 

 days, and both the axes and the residual seeds analyzed separately. 



INORGAmC CONSTITUENTS. 



SEEDLINGS GROWN IN DISTILLED WATER. 



POTASH ABSORPTION. 



To show with what avidity and activity these little seedlings take 

 up potash, figure 1 was platted. This curve shows that when the 

 seedling was 2 days old and weighed about 6 per cent as much as 

 the whole seed (that is, when 100 axes weighed only 0.2 gram), it 

 had absorbed about 50 per cent of the potash of the original seed, as 

 compared with 25 per cent of nitrogen and 17 per cent of phosphoric 

 acid. 



At 4 days, the axes contained almost as much potash as was 

 present in the seed (fig. 2). At the end of 12 days, when the plants 

 were about 6 inches high, and the residual seeds, as shown by figure 2, 

 had given up 96 per cent of their potash, 83 per cent of their nitrogen, 

 and 80 per cent of their phosphoric acid, the axes contained half again 

 as much potash, 93 per cent as much nitrogen, and 75 per cent as 

 much phosphoric acid as did the original seed. The explanation 

 given of this high absorption of potash is that on steeping, the seeds 

 excrete large amounts of this plant food, which are rapidly absorbed 

 by the seedling, the extra amount of potash coming from the ungermi- 

 nated seeds. This fact was proved by the following experiment: 

 10 grams of wheat seeds were shaken with 100 cc of water and allowed 



94089°— Bull. 138—11 2 



