INOKGANIC CONSTITUENTS. Il 



potash which have been absorbed; that is, while the weight of the 

 radicle increases from 10 to 18 per cent the increase of phosphoric 

 acid ranges from 17 to 27 per cent, the increase in nitrogen varies 

 between 23 and 32 per cent, and the amount of potash remains prac- 

 tically constant at about 24 per cent. The amounts of nitrogen, 

 phosphoric acid, and potash in the radicle indicate that almost as 

 soon as absorbed these elements are translocated to the plumule, 

 where they can be utilized during the subsequent processes of assimi- 

 lation and plant growth. 



At the age of three days in the water culture the weights of the 

 plumule and radicle are about equal; the plumule has, however, 

 about twice as much nitrogen and potash and a half again as much 

 phosphoric acid as is present in the radicle. 



At the end of seven days the plumule weighs almost twice as much 

 as the radicle, contains over twice as much nitrogen and phosphoric 

 acid, and about four times as much potash, showing that potash is 

 the element especially accumulated in the plumule. 



The latter part of Table 3 shows to what extent these conditions 

 are accentuated when seedlings are grown in a nutrient solution. On 

 the fifth day of the experiment the weights of the plumule and of the 

 radicle were almost identical and the amounts of nitrogen and phos- 

 phoric acid in each were approximately the same, and the potash in 

 the plumule was about twice that in the radicle. At the end of 15 

 days the plumule weighed more than twice as much as the radicle 

 and contained over 2 J times as much nitrogen, nearly 4 times as 

 much phosphoric acid, and about 17 times as much potash. This 

 is a most striking illustration of how the absorbed salts are moved 

 from the radicle to the plumule and there accumulated; especially 

 is this true of the potash, and when taken in connection with the 

 rapid breaking down of the starch and sugars (see p. 28) would seem 

 to indicate that potash pla^^s the chief physiological role in these 

 changes. 



There was a steady increase in the weights of the plumule and in 

 the amount of nitrogen, phosphoric acid, and potash therein, the 

 weight increasing 9 times, the nitrogen almost 7 times, the phosphoric 

 acid about 15 times, and the potash about 17 times. The weight of 

 the radicle increased twice, the nitrogen was almost double, and the 

 phosphoric acid increased 2^ times, while the potash actually showed 

 a decrease, thus indicating that as far as this constituent is concerned, 

 the plumule is really the seat of physiological action. 



A further comparison of these data shows that at the beginning of 

 the experiment the weights of the radicles and the amounts of nitro- 

 gen and phosphoric acid therein in the case of the seedlings grown in 

 distilled water are about the same respectively as the figures found 

 for the radicles of the seedlings grown in the nutrient solution. The 



