522 
Philippine Journal of Science 
1920 
kation of one of the three salts used, which means that its in- 
troduction can be accomplished (in a 3-salt solution) only by 
omitting either potassium, calcium, or magnesium. 
4. With 3-salt solution type I the nearest approach toward 
good growth was obtained. With solutions in which not more 
than one-eighth of the molecular total is due to calcium nitrate, 
the proportions of the other two salts seem to have been without 
influence in determining which sets of salt proportions were 
least badly balanced. 
5. The best sets of salt proportions of 4-salt solution type A 
gave the most satisfactory growth that was obtained. 
6. The best solutions of type B gave about as good growth 
as did the best ones of type A, by the criteria of size, yield, 
and water-absorption; but even these best solutions of type B 
always produced a marked and characteristic leaf injury, so that 
no solution of this type is to be regarded as at all suited to the 
growth of these plants. This suggests that these young rice 
plants require (at least within the range of these experiments) 
not only the ammonium ion but also the nitrate ion. 
7. The best solution for these plants is one that has a total 
concentration of 0.0016 or 0.0038 gram-molecule per liter (of 
all salts taken together), or an osmotic value of about 0.08 or 
about 0.2 atmosphere. It may be said that the most promising 
total concentration for these plants lies between these limits, 
probably nearer the lower one. The best total concentration 
for young rice plants is thus very much lower than that for 
any other form of plant hitherto studied by these general meth- 
ods. (Wheat thrives best with a total concentration represented 
by an osmotic value of between 1.5 and 2.5 atmospheres.) 
8. For the range of total concentration just mentioned (0.08 to 
0'.2 atmosphere) the best solutions (4-salt type A) are charac- 
terized by having very high relative molecular partial concentra- 
tions of magnesium sulphate. They generally have comparatively 
low relative molecular partial concentrations of monopotassium 
phosphate and calcium nitrate. The most promising solution 
for these plants may be stated as having about 0.002 gram- 
molecule per liter (of all salts), the salts being present in about 
the following molecular proportions; 
KH,PO, : (NHJ :Ca (NO,,) ^ :MgS 04 -l :li :U :4. 
It is safe to say that one very excellent solution would have 
the potassium, ammonium, and calcium salts in about the same 
proportions, while the molecular partial concentration of the 
