THE ASH Of PLANTS. 185 



The concentration of the solution is by no means a 

 matter of indifference. While certain aquatic plants, as 

 sea-weeds, are naturally adapted to strong salipe solutions, 

 agricultural land-plants rarely succeed well in water cul- 

 ture, when the liquid contains more than y^^ of solid 

 matters, and will thrive in considerably weaker solutions. 



Simple well-water is often rich enough in plant-food to 

 nourish vegetation perfectly, provided it be renewed suffi- 

 ciently often. Sachs's earliest experiments were made 

 with well-water. 



Birnerand Lucanus, in 1864 ( Vs. St., YIII, 154), raised 

 oat-plants in well-water, which in respect to entire weight 

 were more than half as heavy as plants that grew simul- 

 taneously in garden soil, and, as regards seed-production, 

 fully equalled the latter. The well-water employed con- 

 tained but ^^ of dissolved matters, or in 100,000 parts: 



Potash 2.10 



Lime 15.10 



Magnesia 1.50 



Phospliorlo acid 0.16 



Sulphuric acid 7.50 



Nitric acid. 6.00 



Silica, Chlorine, Oxide of iron traces 



Solid Matters 32.36 



Water 99,967.64 



100,000 



On the other hand, too great dilution is fatal to growth. 

 Nobbe { Vs. St., VIII, 337) found that in a solution con- 

 taining but TTi^TTjr of solid matters, which was continually 

 renewed, barley made no progress beyond germination, 

 and a buckwheat plant, which at first grew rapidly, was 

 soon arrested in its development, and yielded but a few 

 ripe seeds, and but 1. 746 grm. of total dry matter. 



While water-culture does not provide all the normal 

 conditions for the growth of land plants — the soil having 

 important functions that cannot be enacted by any liquid 

 medium — it is a method of producing highly-developed 

 plants, under circumstances which admit of accurate con- 



