98 BOTANICAL GAZETTE [FEBRUARY 
lies very close to the green weight curve, and is generally parallel to 
it. The upper part of the transpiration curve, which lies somewhat 
below the green weight curve, may probably be regarded as showing 
a retardation of transpiration in those examples. 
Fig. 8, showing the relationship between green weight and trans- 
Fic. 9.—Correlative growth and 
transpiration in soil extracts to which 
aCO, was added 
piration in cultures to which 
Na,HPO, was added, may be 
regarded as a general indication of 
the effect of the PO, ion. The 
transpiration here appears to be 
generally higher than thecorrelative 
green weight and is accordingly 
consonant with former results. 
The effects of CaCO,, as shown 
by the curves in jig. 9, is very 
accelerating upon transpiration. 
Although the transpiration curve 
is subject to somewhat extreme 
fluctuation, all its points lie above 
the green weight curve and the 
mean of the transpiration curve 
lies far above. 
It may be said that, in the main, 
the salts had the same effect when 
added to soil extracts as when 
added to the soil in which plants: 
were grown, although, in the case 
of CaCO, the results were some- 
what more emphasized in the soil 
extracts. 
The next studies taken up were 
devoted to the effect of acids and alkalies upon transpiration. This 
question has previously been studied by numerous investigators, 
notably SENEBIER, SACHS, and BURGERSTEN, all of whom apparently 
agree in showing that the addition of a small amount of an acid 
increases the transpiration, while the addition of a small amount of 
alkali decreases transpiration. 
ee 
