rather above .01 of an inch in width; but they were not so sharp and regular as those made by Phalaris and Avena, and therefore could not be so easily measured under the microscope.  The hypocotyls were found, when the sand was removed on one side, to be curved to a depth beneath the surface in three cases of at least .1 inch, in a fourth case of .11, and in a fifth of .15 inch.  The chords of the arcs of the short, buried, bowed portions formed angles of between 11o and 15o with the perpendicular.  From what we have seen of the impermeability of this sand to light, the curvature of the hypocotyls certainly extended down to a depth where no light could enter; and the curvature must have been caused by an influence transmitted from the upper illuminated part.

The lower halves of five young hypocotyls were surrounded by unpainted gold-beaters’ skin, and these, after an exposure of 8 h. before a paraffin lamp, all became as much bowed to the light as the free seedlings.  The lower halves of 10 other young hypocotyls, similarly surrounded with the skin, were thickly painted with Indian ink; their upper and unprotected halves became well curved to the light, but their lower and protected halves remained vertical in all the cases excepting one, and on this the layer of paint was imperfect.  This result seems to prove that the influence transmitted from the upper part is not sufficient to cause the lower part to bend, unless it be at the same time illuminated; but there remains the doubt, as in [page 482] the case of Phalaris, whether the skin covered with a rather thick crust of dry Indian ink did not mechanically prevent their curvature.

Beta vulgaris.—­A few analogous experiments were tried on this plant, which is not very well adapted for the purpose, as the basal part of the hypocotyl, after it has grown to above half an inch in height, does not bend much on exposure to a lateral light.  Four hypocotyls were surrounded close beneath their petioles with strips of thin tin-foil, .2 inch in breadth, and they remained upright all day before a paraffin lamp; two others were surrounded with strips .15 inch in breadth, and one of these remained upright, the other becoming bowed; the bandages in two other cases were only .1 inch in breadth, and both of these hypocotyls became bowed, though one only slightly, towards the light.  The free seedlings in the same pots were all fairly well curved towards the light; and during the following night became nearly upright.  The pots were now turned round and placed before a window, so that the opposite sides of the seedlings were exposed to the light, towards which all the unprotected hypocotyls became bent in the course of 7 h.  Seven out of the 8 seedlings with bandages of tin-foil remained upright, but one which had a bandage only .1 inch in breadth, became curved to the light.  On another occasion, the upper halves of 7 hypocotyls were surrounded with painted gold-beaters’ skin; of these 4 remained upright, and 3 became a little curved to the light:  at the same time 4 other seedlings surrounded with unpainted skin, as well as the free ones in the same pots, all became bowed towards the lamp, before which they had been exposed during 22 hours.