COMPOSITION IN SUCCESSIVE STAGES. 237 



These two independent investigations could hardly 

 give all the discordant results observed on comparing 

 the above figures, as the simple consequence of the 

 unlike mode of conducting them. We observe, for 

 example, that in the last period Arendt's plants gathered 

 less silica than in any other only 7 per cent of the 

 whole. On the other hand, Bretschneider's crop gained 

 more silica in this than in any other single period, viz. : 

 28 per cent. A similar statement is true of phosphoric 

 oxide, f It is obvious that Bretschneider's crop was tak- 

 ing up fixed matters much more vigorously in its last 

 stages of growth than were Arendt's plants. As to 

 potash, we observe that its accumulation ceased in the 

 4th Period in both cases. 



C. Translocation of Substances in the Plant. 

 The transfer of certain matters from one part of the 

 plant to another during its growth is revealed by the 

 analyses of Arendt, and since such changes are of inter- 

 est 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 carbhy- 



*In these instances Bretschneider's later crops appear to contain less 

 sulphuric oxide, lime and potash, than the earlier. Thisresult maybe 

 due to the washing of the crop by rains, but is probably caused by 

 unequal development of the several plots. 



t Phosphoric oxide is the "phosphoric acid," P 2 O S , of older and to a 

 great degree of current usage. See p. 163. 



