140 Macfarlane, The Sensitive Movements of some Flowering Planta. 



plant 1 and to a certain extent 2 presented irregulär positions of 

 the leaves, that were in striking contrast to the uniform position 

 of those on plants 3 and 4 or on exposed leaves. 



September 7 th. The day throughout was clear and wann. 

 At 7:45 a. m. the shade temperature was 2ö° C, but plants 

 exposed to the sun had moved through an angle of 10 — 15°. The 

 leaflets of screened plants were all flat. At 10:30 the shade tem- 

 perature was 29° C, and under the screens was 34—35.5° C. 

 Plants 1 and 2 had their leaflets inostly deflexed; a few only of 

 the lower and older leaflets were flat, or nearly so. The leaflets 

 of plant 3 remained quite flat, those of plant 4 had inflexed through 

 an angle of 30 — 35°. These relative positions were maintained 

 during the day tili 4:15, when plant 4 gradually recovered its 

 expanded State. At 4: 10 plant l began to show nyctitropism, and 

 bv 4:50 the leaflets had closed. The same irregularity of leaf 

 and leaflet movement was exhibited as on previous days. At 4:30 

 the leaflets of plant 2 had slightly inflexed on the younger leaves. 

 and by 5:20 most of the leaflets were closed. At 5:10 plant 3 

 and likewise exposed plants had moved, and by 5:5) the leaflets 

 were partly closed. At 5:40 the leaflets ot plant 4 had started, 

 bnt at this stage the observations were stopped. 



Plants in pots were next set out, and alongside the screened 

 ones were placed three as control specimens to indicate ordinary 

 behavior under sunlight. One of the three was set against a white 

 back-ground, the other two were set on grass. The plants were 

 so situated that they received direct sunlight from 8:50 a. m. 

 onwards. They were set out on the afternoon of September 10 th, 

 but from unavoidable circumstances observations could not be 

 made tili September 12 th. 



September 12 th. The sky during the day was clear and 

 the sunlight streng. At 7:30 a. m. the temperature was 19° C 

 in the shade, and all of the plants had their leaflets fully exposed. 

 By 10:15 the temperature in the sun was 33.5° C and in the 

 shade 26° C, while under the screens it varied from 31 — -33° C. 

 The leaflets of 1 were slightly deflaxed, those of 2 were flat, those 

 of 3 were flat in the older leaves, but slightly inflexed in the 

 younger ones, those of 4 were inflexed 10—15°. At 11:30 the 

 leaflets of 1 were deflexed 5 — 8°, a few of those under 2 were 

 slightly deflexed, but most were flat, those of 3 had not sensibly 

 altered, the leaflets of 4 were now inflexed from 35 — 40°. The 

 last position corresponded with that of the leaflets placed against 

 the white surface, and was greater by about 10° than that shown 

 bythe plants on the lawn. The above relative positions were retained 

 tili 4:15, except that on three occasions rather dense, dull-white 

 clouds floated across the sun's disc, and caused on each occasion 

 expansion of the leaflets of 4 through 5 — 10°. The leaflets of 

 I had begun to ineurve at 4:15, those of 2 at 4:45, those of 3 

 at 5.5 and of 4 at 5:40. By 6:35 all had closed. 



