49 NEW ZEALAND NATURE-STUDY BOOK 
The following culture solutions—either of which may be 
used with success—do not contain the element carbon. It 
is this fact, taken in connection with what we have already 
learnt, which clearly shows that the necessary carbon is 
obtained from the carbon-dioxide of the air. 
(A) Potassic nitrate ... 1 Gram. 
Calcic sulphate 
Magnesic sulphate 
Calcic phosphate 
Sodic chloride 
Dol bo Dol role 
Ferrous sulphate ... A trace 
Water... - 1 litre 
(B) Potassic nitrate ... 2 Grams 
Calcic phosphate .. 1 Gram 
Magnesic sulphate ... 1 ,, 
Ferric chloride ... <A trace 
Water... .. 2 litres 
NotTE.—None of the work in this chapter should be attempted 
below Standard ITI.; most of it will probably be taken up in the 
higher classes. All the experiments—which will take a long 
time to work out—should be undertaken by the pupils themselves. 
That is, the pupils should fix up the necessary apparatus, and 
should give special attention to dates and to detailed descriptions 
of what they have done, observed, and learnt. 
In the case of the cultivation of plants in artificial soils and in 
solutions, quite a good deal of investigation could be carried out 
in the direction of determining the inorganic substances essential 
for growth. Both water and sand or some substance of the kind, 
should be used in this connection. 
X.—CONDITIONS ESSENTIAL TO GROWTH. 
—_—$__—__ 
(1) The plant or seed must be living; it is impos- 
sible to induce a dead plant of any kind to grow. Ifa dead 
pea or bean seed be placed in damp sawdust or moist ground, 
