THE ASH OP PLANTS. 



167 



Experiments ia Solutions.— Water-Culture— Sachs, 



W. Knop, Stohmann, Nobbe, Siegert, and others have 

 likewise studied this subject. Their method was like that 

 of Prince Salm-Horstmar, except that the plants were 

 made to germinate and grow independently of aay soil ; 

 and, throughout the experiment, had their roots immersed 

 in water, containing in solution or suspension the sub- 

 stances whose action was to be observed. 



Water- Culture has recently contributed so much to our 

 knowledge of the conditions of vegetable growth, that 

 some account of the mode of conducting it may be proper- 

 ly given in this place. Cause a 

 number of seeds of the plant it is 

 desired to experiment upon to ger- 

 minate in moist cotton or coarse sand, 

 and when the roots have become an 

 inch or two in length, select the 

 strongest seedlings, and support them, 

 so that the roots shall be immersed in 

 water, while the seeds themselves shall 

 be just above the surface of the liquid. 



For this purpose, in case of a single 

 maize plant, for example, provide a 

 quart cylinder or bottle, with a wide 

 mouth, to which a cork is fitted, as in 

 Fig. 22. Cut a vertical notch in the 

 cork to its center, and fix therein the 

 stem of the seedling by packing with 

 cotton. The cork thus serves as a 

 support of the plant. Fill the jar 

 Avith pure water to such a height 

 that when the cork is brought to its 

 place, the seed, S, shall be a little 

 above the liquid. If the endosperm 

 or cotyledons dip into the water, they will speedily 

 mould and rot; they require, however, to be kept in 



Fig. 33. 



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