Stem height for the plants of the Baltimore covered station 

 are above the corresponding values for the exposed station. 

 Also, the tendency of the plants under the glass to elongate 

 relatively more han t e exposed plants is shown by the stem 

 height values for the Baltimore covered station for both two 

 and four weeks of growth. It is interesting to note that 

 the covered plants do not show high values of the plant growth 

 rates for the period beginning Aug. 6 as do the exposed plants. 

 The four-week graphs for the covered plants show very well the 

 tendency of leaf area to reach values relatively higher than 

 dry weight, the leaf area grat)h being well above the dry 

 weight graph for the entire season. 



For Easton the covered plants, as compared with the ex- 

 posed, show the general tendencies noted above. The two-week 

 growth rates of the covered plants are higher than those of the 

 exposed plants especially stem height. It will be observed 

 that the maximum growth for the season in both the covered 

 and exposed two-week cultures occurs in the petiod beginning 

 Aug. 3. The four-week olaAts of the covered cultures sho'-: 

 leaf area relatively higher than dry weight. The values for 

 the culture period beginning June 22 are low for the covered 

 cultures as well as in the exposed set. It was noted in the 

 discussion of the latter that the climatic averages and these 

 low values did not correlate. Since the covered plants show 

 low values as well as the exposed. It is likely that we are 

 dealing here with some climatic effect, however, and not 

 with an abnormality of the cultures. 



The difference between the behavior of the plants under 

 glass and those in the open should be attributed, it would 



