Mel Hot us alba, L. and other Plants. "\ 



This may account for some of the difference. The stomata 

 were well open both in the plant under alum and in the one 



packed in ice. 



PI. X, Fig. 3 shows a photograph of a plant taken from 

 the west on a clear evening at six o'clock, after a shower. 

 The lower leaflets have turned on edge, and others dropp.d 

 down vertically in order to receive the sun's rays at right an- 

 gles to their surfaces. It is to be compared with PI. X, 

 Fig. 4, taken on an excessively dry evening at the same hour. 

 In the latter all the leaves are pointing directly west. The 

 photograph was taken from the north. 



Experiment No. 4. — Four plants were placed on the lawn 

 and covered with red, blue, opaque or black, and white glass 

 respectively. 



The one under blue glass seemed quite as active in the 

 movement of its leaves as the one under white glass. The 

 one under red glass lost very soon nearly all of its directive 

 motion from the sun, and its leaves made a slight advance 

 toward a sleeping position. The sleep position was assumed 

 nearly two hours earlier under the red glass than under the 

 blue or the white. It was also found that plants under red 

 glass put their leaves in a very different sleep position from 

 plants under either blue or white glass. PL XIII, Fig. 8 

 shows a leaf under red glass, and Fig. 2 the normal sleep posi- 

 tion for comparison. In the former the leaflets are passed 

 down beyond the vertical, then twisted at the pulvini until 

 their under surfaces are all uppermost. PI. XII, Fig. 4 shows 

 a complete plant photographed at twelve o'clock at night from 

 red glass. PI. IX, Pig. 1 was taken from white glass at the 

 same time. 



The plant under opaque or blackened glass lost in a short 

 time its power of motion as stimulated by the sun, and soon 

 went into a semi-sleep position and there remained with some 

 few undulations of motion, which, however, grew less and 

 less and soon disappeared. 



PI. XI, Figs, i^and 4 show photographs from blue and red 

 glass taken on a rainy afternoon at three o'clock. The plant 

 from blue glass with leaves outstretched is trying to get all 



