THE LORANTUACE/E OF CEYLON. 



105 



cotyl to reach the host, since the curvature so characteristic of the hypocotyl of Viscum 

 and Loranthns alike is generally described as due only to the directive influence of lii;ht 

 on growth *. 



This ability of the hypocotyl of L. neelgherrensis to grow and curve in constant 

 darkness was also proved by the following observation : — Ripe seeds of this species were 

 frequently sent to me from the hills. They were picked in the morning, at once enclosed 

 in boxes, and sent off. When any delay caused a day or two to elapse hefore I opened 

 a box, it was invariably the case that many of the seeds had begun to germinate, the 

 hypocotyl projecting (coiled up, or at least much curved) througli the seed-coat, which 

 itself, till its rupture, cut off all light from the seed (of. figs. 3 and 4, PI. X.). 



It is the same with L. cuneahis, whose fruit, seed, and curious hypocotyl most closely 

 resemble those of L. neelgherrensis. I can speak with less certainty of L. longijlorus 

 (cf. fig. 15, PI. XI.), although it is probable that here too the hypocotyl grows out from 

 the endosperm and curves in the dark. 



But JO. loniceroides and L. neelgherrensis differ in yet another respect, in their reaction 

 to constant darkness. In hoth species the hypocotyls, even whilst enclosed in the 

 endosperm, are green, owing to the presence of chlorophyll ; during growth in the dark, 

 however, the hypocotyl of L. loniceroides loses its green colouring matter and becomes 

 yellow, that of L. neelgherrensis remains vividly green and rich in chlorophyll. 



Prom the point of view of evolution it w^ould he interesting were these observations 

 extended, for there can he scarcely a doubt that a series might be constructed connecting 

 those Loranths which perhaps normally develop in the dark (non-parasites), e. g., 

 L. terrestris, Hook, f., with those which have completely lost the power of germination 



Fig. 5. 



• Feb 8 



Marcm 3 



■^ARCW ?0 



in what was originally their normal manner, viz., in the dark. The loss of this ancestral 

 character seems to be carried far in L. loniceroides, to have hardly occurred in L. neel- 

 gherrensis or L. cuneatus. 



A more immediate interest attaches, however, to the facts just set forth. The 

 hypocotyl of i. loniceroides develops in total darkness but slowly, it is true ; still, in the 

 course of 1 or 2 weeks it reaches a length of 1 cm. or more, and shows frequently distinct 

 curvature. The hypocotyl of X. neelgherrensis in the dark grows more and curves much 

 more. 



* Cf. Guerin, loc. cit. p. 192 et seq. 



