811 



The four-week evaporation graph for Princess Anne is 

 incomplete, the data for the periods tr^glnning May 26, June 8 

 and June 23 not being available, and this renders it diffi- 

 cult to explain the behavior of the plants during the first 

 part of the growing season. The relative temperature index 

 values for this station are high and the eviporation values 

 available for the station all low except the one for the first 

 period of the season. This combination of low evaporation 

 rate and high temperature value would be expected to produce 

 higher rates of growth than were actually shown. The unusu- 

 ally low values of simshine may be related to the fact that 

 the plants failed to show higher dry weights at Princess Anne. 

 It will be seen from the four-week graph that sunshine inten- 

 sity is well below the seasonal average from the period begin- 

 ning June 8 to the end of the season. The behavior of the 

 dry weight fot the first four cultures cannot be satisfactorily 

 explained in the absence of the evaporation data for three of 

 the culture periods but from the peiods beginning July V to 

 the period beginning Sept. 29 inclusive the dry weight and the 

 temperature index values seem to correlate as ^TOuld be expected 

 since evaporation is too lov; to affect the plants and sunshine 

 remains at a nearly constant value during this time. 



All of the plants discussed up to this point were grown 

 In the exposed statins, that is, in the open with no covering 

 other than a screen of wire netting(of large mesh to protect 

 the plants from injury, At three of the stations, Oakland 

 Baltimore, and Easton.as was noted in "he introduction to 

 this paper, a series of cultures was also grown under glared 

 cold-frame sash supported three feet above the ground, these 



