218 HOW CROPS GKOW. 



other single period, viz. : 28 | . A similar statement is 

 true of phosphoric acid. It is obvious that Bretschnei- 

 der's crop was taking up fixed matters much more vigor- 

 ously in its last stages of growth, than were ArendtV 

 plants. As to potash we observe that its accumulation 

 ceased in the 4th period in both cases. 



It is, on the whole, plain that we cannot safely draw from 

 these interesting researches any very definite conclusions 

 as to the rate and progress of assimilation and growth in 

 the oat plant, beyond what have been already pointed out. 



C. Traiislor ation of substances in the Plant. The 



translocation of certain matters from one part of the plant 

 to another is revealed by the analyses of Arendt, and 

 since such changes are of interest from a physiological 

 point of view, we may recount them here briefly. 



It has been mentioned already that the growth of the 

 stem, leaves, and ear, of the oat plant in its later stages 

 probably takes place to a great degree at the expense of 

 the roots. It is also probable that a transfer of amyloids, 

 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 acid passes rapidly from 

 the leaves and stem towards or into the fruit in the earlier 

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

 following figures : 



1,000 plants contained in the various periods, quantities 

 (grams) of phosphoric acid as follows : 



1st Period. 2d Period. M Period, tth Period. 5th 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 



