126 



form, Tlie only difference I have observed was that the West 

 Indian specimens were somewhat larger than the Canary specimen 

 and that the rhizome was glabrous in the former but covered with 

 ramuli in the latter. How far the erect shoots in the Canary spec- 

 imen were flat like the West Indian I am unable to say exactly; 

 judging from M™*^ Weber-van Bosse's Fig. 1 b, PI. XXI the 

 midrib seems in every case to be round, and the same seems to be 

 the case with the basal part of the ramuli; in the description of 

 this species M™^ Weber-van Bosse writes, p. 269 : »Ramules 

 cylindriques a la base«. 



I have further had a specimen from Tongatabu for comparison, 

 collected by Grunow »am Corallenriff«, and to be found in the col- 

 lection of the Botanical Museum in Hamburg. It differs from my 

 specimens by being a little smaller, the erect shoots especially are 

 a little narrower and the ramuli consequently shorter; like the 

 Canary specimen and in contrast to mine the plant from Tongatabu 

 has scattered ramuli. 



Judging from a specimen of mine preserved in formalin and 

 collected in about 50 meters, the shoots are first erect but bend 

 soon to the side in such a way that they turn the flat side upward, 

 probably an adaptation to intercepting the greatest possible 

 amount of light. 



The greater breadth of the erect shoots is also perhaps to be 

 considered as an adaptation both to the quiet place and the 

 feeble light where it grows. 



While it is a common thing in other forms of this species, 

 e. g. f. tomentella, that the erect leaf-bearing shoots bend down- 

 wards at an early stage, obtain rhizoids and grow further on like 

 the rhizomes fixed to the bottom, this is not to be found in the 

 admittedly small material from the West Indies I have had at my 

 disposal. 



If we consider the figure 99 it will easily be observed, that the 

 erect shoots show a very distinctly rhythmical growi^h; every three, 

 or more seldom four, pairs of ramuli are especially well developed 

 and from these the next decrease gradually in size. Such a rhyth- 

 mical growth has also often been found by Svedelius in the Ceylon 

 Caulerpa. How far the segments which arise in this way corres- 

 pond with the growi,h of a year I am unable to say but it seems 

 to me quite natural that this should be the case; I should think 

 that the greatest increase occurs about the month of June when 

 the sun is vertically or nearly vertically above and the light there- 

 fore the most effective. 



