Ricinus Borboniensis (Euphorbiaceae).—­Seeds were purchased under the above name—­probably a variety of the common castor-oil plant.  As soon as an arched hypocotyl had risen clear above the ground, a filament was attached to the upper leg bearing the cotyledons which were still buried beneath the surface, and the movement of the bead was traced on a horizontal glass during a period of 34 h.  The lines traced were strongly zigzag, and as the bead twice returned nearly parallel to its former course in two different directions, there could be no doubt that the arched hypocotyl circumnutated.  At the close of the 34 h. the upper part began to rise and straighten itself, dragging the cotyledons out of the ground, so that the movements of the bead could no longer be traced on the glass.

Quercus (American sp.) (Cupuliferae).—­Acorns of an American oak which had germinated at Kew were planted in a pot in the greenhouse.  This transplantation checked their growth; but after a time one grew to a height of five inches, measured to the tips of the small partially unfolded leaves on the summit, and now looked vigorous.  It consisted of six very thin internodes of unequal lengths.  Considering these circumstances and the nature of the plant, we hardly expected that it would circumnutate; but the annexed figure (Fig. 40) shows that it did so in a conspicuous manner, changing its course many times and travelling in all directions during the 48 h. of observation.  The figure seems to represent 5 or 6 irregular ovals or ellipses.  The actual amount of movement from side to side (excluding one great bend to the left) was about .2 of an inch; but this was difficult to estimate, as owing to the rapid growth of the stem, the attached filament was much further from the mark beneath at the close than at the commencement of the observations.  It deserves notice that the pot was placed in a north-east room within a deep box, the top of which was not at first covered up, so that the inside facing [page 54] the windows was a little more illuminated than the opposite side; and during the first morning the stem travelled to a greater distance in this direction (to the left in the figure) than it did afterwards when the box was completely protected from light.

Fig. 40.  Quercus (American sp.):  circumnutation of young stem, traced on horizontal glass, from 12.50 P.M.  Feb. 22nd to 12.50 P.M. 24th.  Movement of bead greatly magnified at first, but slightly towards the close of the observations—­about 10 times on an average.

Quercus robur.—­Observations were made only on the movements of the radicles from germinating acorns, which were allowed to grow downwards in the manner previously described, over plates of smoked glass, inclined at angles between 65o and 69o to the horizon.  In four cases the tracks left were almost straight, but the tips had pressed sometimes with more and sometimes with less force on the glass, as shown by the varying thickness of the tracks and by little