THE FOOD OF PLANTS. 5 



i 



and bring the research objects (oats, maize, buckwheat, etc.) to 

 complete development and fruit ripening, the cultures will natur- 

 ally require far greater attention, than when the object is merely 

 to prove that green plants in general are able to produce organic 

 substance. 



1. The seeds or fruits are soaked for twelve to twenty-four hours 

 in distilled water, and then germinated in well-washed sawdust 

 loosely filled into flower-pots. (Further particulars have already 

 been given above.) Under some circumstances, and especially in 

 accurate investigations of the requirements of plants as regards 

 mineral substances, it is advisable to germinate the seeds or fruits, 

 after soaking, between folds of Swedish blotting-paper. After 

 soaking the seeds are placed horizontally or vertically between 

 many times folded blotting-paper, which is then fixed upright 

 with its lower end dipping into distilled water, which covers the 

 bottom of a wide-necked glass vessel. The arrangement is finally 

 covered with a bell-glass, the tubulure of which is loosely 

 plugged with cotton wool. 



2. When the roots of the seedlings have attained a length of 

 a few cm., they are transferred to culture vessels of 1-4 litres 

 capacity according to circumstances. The culture cylinders can 

 be closed by means of a cover provided with three openings, and 

 made of japanned sheet zinc, or better of porcelain. The middle 

 opening is fitted with a halved and perforated cork. In this per- 

 foration a seedling is fixed as above described by means of cotton 

 wool. Or we may fix the seedling directly into the opening (about 

 3 cm. in diameter) of the cover without using a cork. The 

 second opening of the cover is closed with a perforated cork, 

 which holds firmly the lower end of a thin wooden rod intended 

 to support the plant during its development. The third opening 

 of the cover is closed with a non-perforated cork. 



3. The shading of the roots in the culture vessels is easily 

 attained by putting these into suitable cardboard cylinders, or by 

 wrapping the cylinders with several layers of flannel. Care must 

 be taken on hot sunny summer days that the food solution does 

 not get too warm. 



4. The culture vessels are placed at the window of a room 

 with a south aspect. It greatly promotes the development of the 

 plants if the culture vessels are placed as often as possible in the 

 open air in front of the window. If we make extended researches 

 every year with the help of the water-culture method, it is very 



