144 Macfarlane, The Sensitive Movements of some Flowering Plants, 



September 22 nd. The day was clear and the sun was 

 rather intense. At 7 : 30 a. m. the leaflets were flat in every plant. 

 At 10:45 plants 1 and 2 showed flat or slightly reflexed leaflets, 

 plant 3 hacl inflexed through 20 — 25°, and 4 through 45 — 50°. 

 This state continued tili 2 : 50, except that as the sunlight became 

 more intense a further inflexion of 4 occurred, the temperature 

 meanwhile being 35° C in the sun and 27.5° C in the shade. 



At 4 : 25 plant 1 began nyctitropic movement, at 4 : 45 plant 

 2 followed, and 3 — which had not as yet recovered froin the 

 paraheliotropic — passed into the nyctitropic state, while 4 that 

 recovered at 5.5 was nearly closed by 7 : 15. 



September 23 rd. The day was clear with warm sunshine, 

 and the records were essentially hke those just given. At 7:45 

 p. m. plant 4 was practically closed. 



Observations could not be made on September 24th, and on 

 the evening of that day the plants were removed. While under 

 the screens specimens 1 and 2 had elongated greatly, specimen 3 

 slightly, and 4 not at all, judging from rough measurement. 



Oxalis striata. 



Seven plants of this species were set out at 7 : 15 a. m. on 

 October 2 nd. Three had been taken from a moist shady corner 

 of my greenhouse, and four had been brought in some days before 

 from a field. This may possible explain the rather varying results 

 recorded below, buth the somewhat low day temperatures and the 

 inuch lower night temperatures may have contributed to these 

 results. The same screens were used as before for four of the 

 plants, and three were used as control specimens. 



By 8 a. m. the leaflets of 1 were deflexed *) through about 

 50°, those of plant 2 were barely one-third deiiexed, those of 

 plants 3 and 4 were flat. At 10 : 30 in a bright sun, plant 1 had 

 leaflets deflexed through 65°, but in 2 the leaflets were re-expanding. 

 The leaflets of 3 were now either flat or inclined upward, forming 

 an angle of 100—105° with the petiole. Plant 4 showed insolation 

 effects, the leaflets being deflexed 20 — 25°. At 11:30 the tempe- 

 rature was 26° C in the shade, hut the sunlight was intense. 

 Plant 1 had leaflets deflexed through about 80°, plant 2 showed 

 flat or in most cases slightly inflexed leaflets, plant 3 showed flat 

 leaflets, plant 4 showed deflexion of leaflets through 60 — 65°. At 

 12:30 plants 1, 2 and 3 were unaltered, but the leaflets of plant 

 4 were deflexed through 75 — 80°. The observations were inter- 

 rupted tili 4:15, when all the plants except 4 were found to have 

 the leaflets nearly or quite flat. Plant 4 now recovering from 

 paraheliotropism was still deflexed through 25°, and at 5:20 its 

 leaflets were flat, but at that time none showed nyctitropism. 



At 5 : 30 plant 1 had slightly reflexed, and by 5 : 45 plant 2, 

 as well as exposed specimens. At 6 : 30 plant 1 had closed, 



*) It will be remembered that Oxalis leaflets fall backward or become 

 deflexed as a result of Stimulation. 



