Trifolium repens.—­A stem was secured close to the base of a moderately old leaf, and the movement of the terminal leaflet was observed during two days.  This case is interesting solely from the simplicity of the movements, in contrast with those of the two preceding species.  On the first day the leaflet fell between 8 A.M. and 3 P.M., and on the second between 7 A.M. and 1 P.M.  On both days the descending course was somewhat zigzag, and this evidently represents the circumnutating movement of the two previous species during the middle of the day.  After 1 P.M., Oct. 1st (Fig. 144), the leaflet began to rise, but the movement was slow on both days, both before and after this hour, until 4 P.M.  The rapid evening and nocturnal rise then commenced.  Thus in this species the course during 24 h. consists of a single great ellipse; in T. resupinatum of two ellipses, one of which includes the nocturnal movement and is much elongated; and in T. subterraneum of three ellipses, of which the nocturnal one is likewise of great length.

Securigera coronilla (Tribe 4).—­The leaflets, which stand opposite one another and are numerous, rise up at night, come into close contact, and bend backwards at a moderate angle towards the base of the petiole. [page 353]

Fig. 144.  Trifolium repens:  circumnutation and nyctitropic movements of a nearly full-grown terminal leaflet, traced on a vertical glass from 7 A.M.  Sept. 30th to 8 A.M.  Oct. 1st.  Nocturnal course, represented by curved broken line, much abbreviated.

Lotus (Tribe 4).—­The nyctitropic movements of 10 species in this genus were observed, and found to be the same.  The main petiole rises a little at night, and the three leaflets rise till they become vertical, and at the same time approach each other.  This was conspicuous with L. Jacoboeus, in which the leaflets are almost linear.  In most of the species the leaflets rise so much as to press against the stem, and not rarely they become inclined a little inwards with their lower surfaces exposed obliquely to the zenith.  This was clearly the case with L. major, as its petioles are unusually long, and the leaflets are thus enabled to bend further inwards.  The young leaves on the summits of the stems close up at night so much, as often to resemble large buds.  The stipule-like leaflets, which are often of large size, rise up like the other leaflets, and press against the stem (Fig. 145).  All the leaflets of L. Gebelii, and probably of the other species, are provided at their bases with distinct pulvini, of a yellowish colour, and formed of very small cells.  The circumnutation of a terminal leaflet of L. peregrinus (with the stem secured) was traced during two days, but the movement was so simple that it is not worth while to give the diagram.  The leaflet fell slowly from the early morning till about 1 P.M.  It then rose gradually at first, but rapidly late in the evening.  It occasionally stood still for about 20 m. during the day, and sometimes zigzagged a little.  The movement of one of the basal, stipule-like leaflets was likewise traced in the same manner and at the same time, and its course was closely similar to that of the terminal leaflet.