100 



MR. F. W. KEEBLE ON 



the hypocotyl does not grow out, but swells and shows no sign of curvature. Attachment 

 to the host nevertheless occurs, the " root- structure " growing out from the shaded side 

 at the point of contact with the host. I grew a number of such seedlings on bottle-cork 

 and preserved them in spirit, in order, subsequently, to ascertaia by sections whether any 

 slight curvature, imperceptible to the eye, does occur. If not, the conclusion must be 

 adopted that in this form the smallness of the seed and the confinement of the viscin 

 to the hypocotyl-end of the seed enables this hypocotyl to dispense with any negatively 

 heliotropic curvature. 



Lorantlms loniceroides. — A ripe seed removed from its fruit-coat begins at once to 

 germinate. A resinous droj^ appears at the apex — being pushed out by the head of the 

 hypocotyl. Then the hypocotyl itself appears ; its general surface, even whilst within 

 the endosperm, is bright green, owing to the presence of chlorophyll; but the free distal 

 surface of its head is whitish, except for a central reddish point and for a green rim 

 (fig. 5<?, PL XI.). The whole surface of the hypocotyl is sticky. 



Fia. 2. 



The cotyledons are yellowish, linear, and not fused. The outgrowing hypocotyl is at 

 first straight, but soon curves (figs. 5a-<?, PL XL). 



The seed is usually found disposed more or less vertically, apex upward, on a branch, so 

 that the hypocotyl, by its curvature, brings its free end or ' suctorial disc ' on to the host. 



The disc, on coming into contact with a branch, swells considerably, and the cells of its 

 distal surface grow out and enter the host as papilla? (fig. 6/, PL XL, and woodcut 2, 

 which represents a vertical section through the hypocotyledonary disc of a seedling of 

 L. loniceroides grown on bottle-cork). 



The seedling thus arrives at the position indicated in fig. 6 c/, PL XL The growth of 

 the hypocotyl now becomes greatest on its concave side, and, since the sucker is firmly 

 attached, the viscin, which holds the base of the seed to the branch, is torn away and the 

 seed carried upward. By this growth the axis of the hypocotyl becomes once more a 

 straight line, and the seed is borne in a line with this axis. 



