1910] REED—TRANSPIRATION AND GROWTH OF WHEAT 95 
commonly used as fertilizers. A few cases in each series gave growth 
somewhat less than the controls and others were practically equal to 
the controls, but a goodly number in each series gave material sis, ane 
in the positive direction. On account of a smaller number of See 
ments, not so many comparisons are possible, however, as in the 
case of the former series. eid 
One feature associated with the growth of wheat plants in soil 
extracts or nutrient 
solutions is deserving 
of especial mention. 
When the compounds 
added to a medium 
caused (as many of 
them did) a material 
increase in root 
growth, there was 
usually a correspond- 
ing increase in trans- 
piration, regardless of 
whether the growth of 
the green parts of the 
plants was greatly in- 
creased or not. It is 
held that the increase 
in size of the absorp- 
tive System is con- Fic. 6.—Correlative growth and transpiration in 
mected in some way soil extracts to which K,SO, was added. 
With an accelerating : : Fe 
action upon the escape of water from the subaerial portions 0 
plant. : 
The first computations are concerned with the units aie 
required to produce a unit of green weight, and the influence of variou 
Compounds thereupon. ; 
The plants soe in soil extract to which sodium nitrate jee 
added showed a transpiration per unit green growth ak LE Re 
of transpiration in the controls. Similarly, the cate’ paca = ei 
€xtract plus potassium sulfate was 85.3 per cent.; in extracts p 
