in the 3 h. by the apex of this leaflet was 1.03 inch.  If we look at the figure, and prolong upwards in our mind’s eye the short curved broken line, which represents the nocturnal course, we see that the latter movement is merely an exaggeration or prolongation of one of the diurnal ellipses.  The same leaflet had been observed on the previous day, and the course then pursued was almost identically the same as that here described.

* ‘Flora,’ 1863, p. 497.

** ‘Die Period.  Bewegungen,’ 1875, pp. 35, 52. [page 351]

Fig. 142.  Trifolium subterraneum:  circumnutation and nyctitropic movement of terminal leaflet (.68 inch in length), traced from 6.45 A.M.  July 4th to 9.15 A.M. 5th.  Apex of leaf 3 7/8 inches from the vertical glass, and movement, as here shown, magnified 5 1/4 times, reduced to one-half of original scale.  Plant illuminated from above; temp. 16o — 17o C.

Trifolium resupinatum.—­A plant left entirely free was placed before a north-east window, in such a position that a terminal leaflet projected at right angles to the source of the light, the sky being uniformly clouded all day.  The movements of this leaflet were traced during two days, and on both were closely similar.  Those executed on the second day are shown in Fig. 143.  The obliquity of the several lines is due partly to the manner in which the leaflet was viewed, and partly to its having moved a little towards the light.  From 7.50 A.M. to 8.40 A.M. the leaflet fell, that is, the awakening movement was continued.  It then rose and moved a little laterally towards the light.  At 12.30 it retrograded, and at 2.30 resumed its original course, having thus completed a small ellipse during the middle of the day.  In the evening it rose rapidly, and by 8 A.M. on the following morning had returned to exactly the same spot as on the previous morning.  The line representing the nocturnal course ought to be extended much higher up, and is here abbreviated into a short, [page 352] curved, broken line.  The terminal leaflet, therefore, of this species described during the daytime only a single additional ellipse, instead of two additional ones, as in the case of T. subterraneum.  But we should remember that it was shown in the fourth chapter that the stem circumnutates, as no doubt does the main petiole and the sub-petioles; so that the movement represented in Fig. 143 is a compounded one.  We tried to observe the movements of a leaf kept during the day in darkness, but it began to go to sleep after 2 h. 15 m., and this was well pronounced after 4 h. 30 m.

Fig 143.  Trifolium resupinatum:  circumnutation and nyctitropic movements of the terminal leaflet during 24 hours.