104 L.8.C. Proceedings of the Ninth [N.S., XVIII, 
closely paralleling the transpiration of plants exposed to 
similar conditions, with plenty of water available. In nature, 
however, maximum transpiration occurs during the dry season, 
when available soil moisture is at a minimum. any of our 
common crop and characteristic wild plants should be studied 
with regard to their water demands. Jt is probable that the 
results would be of great value to agriculture, especially in 
connection with the search for varieties suitable for growing 
in the various parts of the country 
Light relations—GaRNER AND ALLARD! have shown 
that the number of hours of daily illumination is one of the most 
important factors in regulating the vegetative and reproductive 
phases of plants. They find in the species they have studied 
that ‘‘ normally the plant can attain the flowering and fruiting 
stages only when the length of day falls within certain limits, 
and, consequently, these stages of development ordinarily 
are reached only during certain seasons of the year. In this 
particular, some species and varieties respond to relatively 
ong days, while others respond to short days, and still others 
are capable of responding to all lengths of the day which 
prevail in the latitude of Washington where the tests were 
made’’ (p. 603). This opens up a wide new field for expeti- 
mental work. It is entirely likely that the failure of certain 
cuous success of others may be due in large part to their differ- 



} GaRNER, W. W. and H. A. Attarp. The effect of relative length 
of day and night and other factors on growth and reproduction in plants. 
Jour. Agric. Res. 18 : 553-606. 1920. 
* WatsterR, H. L. Formative effect of high and low temperatures 
hy on growth of barley: a critical correlation. Bot. Gaz. 69 : 97-126. 
