Ipomoea coccinea.—­The cotyledons whilst young do not sink at night, but when grown a little older, but still only .4 inch in length (measured as before) and .82 in breadth, they became greatly depressed.  In one case they were horizontal at noon, and at 10 P.M. one of them stood at 64o and the other at 47o beneath the horizon.  The blades are thin, and the petioles, which become much curved down at night, are short, so that here weight can hardly have produced any effect.  With all the above species of Ipomoea, when the two cotyledons on the same seedling were unequally depressed at night, this seemed to depend on the position which they had held during the day with reference to the light.

Solanum lycopersicum (Solaneae).—­The cotyledons rise so much at night as to come nearly in contact.  Those of ‘S. palinacanthum’ were horizontal at noon, and by 10 P.M. had risen only 27o 30 minutes; but on the following morning before it was light they stood at 59o above the horizon, and in the afternoon of the same day were again horizontal.  The behaviour of the cotyledons of this latter species seems, therefore, to be anomalous. [page 307]

Mirabilis jalapa and longiflora (Nyctagineae).—­The cotyledons, which are of unequal size, stand horizontally during the middle of the day, and at night rise up vertically and come into close contact with one another.  But this movement with M. longiflora lasted for only the three first nights.

Beta vulgaris (Polygoneae).—­A large number of seedlings were observed on three occasions.  During the day the cotyledons sometimes stood sub-horizontally, but more commonly at an angle of about 50o above the horizon, and for the first two or three nights they rose up vertically so as to be completely closed.  During the succeeding one or two nights they rose only a little, and afterwards hardly at all.

Amaranthus caudatus (Amaranthaceae).—­At noon the cotyledons of many seedlings, which had just germinated, stood at about 45o above the horizon, and at 10.15 P.M. some were nearly and the others quite closed.  On the following morning they were again well expanded or open.

Cannabis sativa (Cannabineae).—­We are very doubtful whether this plant ought to be here included.  The cotyledons of a large number of seedlings, after being well illuminated during the day, were curved downwards at night, so that the tips of some pointed directly to the ground, but the basal part did not appear to be at all depressed.  On the following morning they were again flat and horizontal. the cotyledons of many other seedlings were at the same time not in any way affected.  Therefore this case seems very different from that of ordinary sleep, and probably comes under the head of epinasty, as is the case with the leaves of this plant according to Kraus.  The cotyledons are heliotropic, and so is the hypocotyl in a still stronger degree.