!9oS] TR^^NSEAU— PLANT SOCIETIES AND EVAPORATION 



219 



the instrument, the porous cup and tube were completely filled with 



water and the jar was filled to a mark near the top. At convenient 



mtervals the loss of water by evaporation was determined by running 



in water from a burette and restoring the original water level. Because 



of the large water area in the jar the error in these readings is estimated 

 to be ±1'"'. 



Following are the vaporimeter readings for the several habitats, 

 with their accompanying vegetation. The corresponding record for 

 the standard instrument is given in 

 each case, together with the com- 

 parative evaporation expressed in 

 percentages of the standard. 



Station i (standard) .—Located 

 in the east plot of the garden of 

 the Station for Experimental Evo- 

 lution; altitude above sea-level 

 about 



the area adjacent to the vapor- 





During the summer 



Oenothera nanella, set 



plant 



I 



m 



from 



the 



itrument and from each 



size of this 



other. The small 

 variety of evening 

 the instrument freely exposed to 



primro 



left 



the 



sun and air. The soil is 



a 



dark-colored sandy loam {figs. 



^.J). 



Fig. 2. — Standard instrument m position 



AmOUXT of evaporation by -Vi^EKS 



Week ending May 27, 197^^ 



June 3, 106 

 June 10, 122 

 June 17, 153 

 June 24, 166 



Week ending July 



8, 152 



a 



a 



a 



a 



i< 



a 



u 



li 



a 



u 



July 



I, 129 



u 



ii 



a 



h fr 



ii 



ii, 



4£ 



ii 





ii 



July i5t 152 



July 22, 1x4 

 July 29, 160 

 August 4, 102 

 August II, 104 



Station 



2. 



Total for 12 weeks, 1657^^ 



.\ garden plot between Hillside and Highland avenues, 



Huntington, about 3^^ east of the standard. Conditions similar to 

 those at the Carnegie garden, except the elevation, which is about 



