88 BOTANICAL GAZETTE [FEBRUARY 
The plants to which nitrate was added showed noticeable greening 
in 4 or 5 days, and somewhat later became a normal green. Not 
only did the new leaves put forth become green, but even the light 
yellow leaves which were on at the time the nitrate was added 
became green. 
Another set of experiments was carried out in which the elements 
Mg, N, P, Ca, and Fe were added to plants growing in pots in 
ordinary potting soil (figs. 3, 4). The solutions used were 2 per 
cent FeCl,, 1 per cent MgCl, 6 per cent CaCl, 2 per cent KH,PO,, 
and 8 per cent NaNO,. Eight plants were used for each treatment 
and 8 for controls, making 48 in all. In each case 0.25 cc. of the 
salt solution, diluted to 6.25 cc., was applied to the soil in the 
pots three times a week. In addition to this the plants were 
watered daily with tap water. The plants to which iron was added 
were given two or three drops of the iron solution each week. 
Some of the plants before being placed under treatment had 
already begun to mottle, but those to which nitrate was added 
rapidly regained their normal green. All of the plants to which 
nitrate was added retained their normal green and held their 
leaves better than the other cultures; also they branched and were 
sturdier than the rest. The plants shown in fig. 3 were grown 4 
months in 2-inch pots, while those shown in fig. 4 were grown 
4 months in 3-inch pots. Plants which were used as controls did 
not seem to do as well as the others, while the plants which received 
phosphate lost a large percentage of their leaves. The plants 
which received magnesium, calcium, or iron grew about equally 
well. The data given in table II show that lack of phosphate 
seemed to cause leaf fall, while here its addition caused the same 
effect. The lack of phosphates caused the leaf to fall, while the 
addition of phosphates alone to the soil, the nutrients not being 
present in a balanced ratio, produced the same effect. 
Dicxkson’s (12) work on oats is of interest in this connection. 
He found that oat seedlings grown in solutions deficient in phos- 
phorus or nitrogen produced but one slender shoot. Plants 
grown in solutions deficient in Ca or Mg stooled heavily before 
those grown in complete nutrient solutions, and later the plants 
grown in solutions deficient in magnesium showed marked striping 
