238 HOW CROPS GROW. 



drates, and certain that one of albuminoids, goes on from 

 the leaves through the stem into the ear. 



Silica appears not to be subject to any change of posi- 

 tion after it has once been fixed by the plant. Chlorine 

 likewise reveals no noticeable mobility. 



On the other hand, phosphoric oxide passes rapidly from 

 the leaves and stem towards or into the fruit in the ear- 

 lier as well as in the- later stages of growth, as shown by 

 the following figures : 



One thousand plants contained in the various periods 

 quantities (grams) of phosphoric oxide as follows : 



1st 2d Zd 4th 5th 



Period. Period. Period. Period. Period. 



3 lower joints of stem, 0.47 0.20 0.21 0.20 0.19 



2 middle " " 0.39 1.14 0.46 0.18 

 Upper joint " 0.66 1.73 0.31 0.39 



3 lower leaves " 1.05 0.70 0.69 0.51 0.35 

 2 upper leaves " 1.75 1.67 1.18 0.74 0.59 

 Ear, 2.36 5.36 10.67 12.52 



Observe that these absolute quantities diminish in the 

 stem and leaves after the 1st or 3d Period in all cases, 

 and increase very rapidly in the ear. 



Arendt found that sulphuric oxide existed to a much 

 greater degree in the leaves than in the stem through- 

 out the entire growth of the oat plant, and that, after 

 blossoming, the lower stem no longer contained sulphur 

 in the form of sulphates at all, though its total in the 

 plant considerably increased. It is almost certain, then, 

 that sulphuric oxide originates, either partially or wholly, 

 by oxidation of sulphur or some sulphurized compound, 

 in the upper organs of the oat. 



Magnesium is translated from the lower stem into the 

 upper organs, and in the fruit, especially, it constantly 

 increases in quantity. 



There is no evidence that Calcium moves upward in 

 the plant. On the contrary, Arendt's analyses go to 

 show that in the ear, during the last period of growth, it 



