THE ASH OP PLAHTS. 213 



slum chloride. II was deprived of potassium save that 

 contained in the seed. In IV and V, respectively, the 

 chlorine of the solution was reduced to one-fourth and 

 one-fifth the amounts contained in the normal solution 

 and replaced by sulphuric acid in IV and by phosphoric 

 acid in V. In case of II 8 , the plant vegetated without 

 potassium for four weeks with a result similar to II, and 

 then for two months was supplied with potassium chlo- 

 ride. For numerous interesting details reference must 

 be made to the original paper (Vs. 8t., XIII, pp. 

 321-424). 



Lupke, from water-cultures with the flowering bean 

 Phaseolus multiflorus, and common bean P. vulgaris, 

 has recently arrived at different conclusions. He finds 

 that these plants are able, under the utmost possible ex- 

 clusion of potassium, to assimilate carbon and produce 

 starch, in fact to grow and to carry on all the vegetative 

 functions that belong to the fully-nourished plant, 

 though on a diminished scale. In order to limit the 

 supply of potassium to the utmost, the cotyledons of some 

 of the plants were cut away when the plumule began to 

 appear above them. In this way 90% of the potassium 

 of the seed was removed* and while the plants were 

 thereby reduced in dimensions, their power to vegetate 

 in a healthy manner was not suppressed. After 65 days 

 of vegetation one of these plants yielded a crop of dry- 

 substance 4.8 times as much as was contained in the 

 newly sprouted seedling after excision of the cotyledons. 



Some results of these cultures are shown in Plate II. 

 The stem of the unmutilated flowering bean in normal 

 solution I, a, reached a final length of 80 inches, that de- 

 prived of potassium grew to 40 inches. 



Nobbe's conclusion that potassium is specifically essen- 

 tial or concerned in starch-production is accordingly erro- 



* Lupke found that one seed of P. multiflorus contained 23 milligrams 

 of potassium oxide; the seedling, after cutting off the cotyledons, con- 

 tains 2.3 mm. 



