APPENDIX A 141 
APPENDIX A 
METHOD OF WATER-CULTURE 
Darwin and Acton, in their ‘ Physiology of Plants’ (p. 59), give the 
following composition of water-culture solution from Sachs: 
Potassium nitrate ... ue oe Ge LO gramme. 
Sodium chloride ... ae as “5 “ 
Calcium sulphate ... oF on: 5 35 
Magnesium sulphate ... —... hy, 
Calcium phosphate . a Ea 
Water a = = “ 1,000-€.c: 
‘One part of the mixture of salts is dissolved in 50 parts of water. 
For use it is diluted to 2 or 8 per mille. A drop or two of iron 
chloride must be added.’ | 
They recommend the use of glass cylinders not less than 700 c.c. 
capacity; also the thorough cleansing of the cylinders first with 
strong commercial nitric acid, removed by distilled water; then 
rinsing with a strong aqueous solution of mercuric chloride, and 
lastly with distilled water which has been boiled for some time 
immediately before use. 
The culture solution should be boiled rapidly for half an hour, 
the water lost by evaporation being replaced by pure distilled water 
and transferred to the cylinder as soon as cooled. 
The plant may be fixed in the cork in cotton- wool, though Darwin 
and Acton find soft asbestos better. Air is let into the cylinder 
through a tube inserted into the cork. If the plants are to keep 
healthy for weeks, the water-culture solution should be renewed at 
the end of each week. 
All these precautions are necessary to prevent the plants being 
attacked by fungi. 
t 
