9 345 



scarcely present here. The locality is quite sheltered and the water for the most 

 part quite clear as no stream is running out here from the land; only during 

 heavy rainfalls the water mingled with mud and sand might naturally come down 

 from the land. Out on the loose bottom itself 1 have not observed C. verticillata 

 and as far as I can discern from the description of Svedei.ius about its mode of 

 life in Ceylon, I may sup|)ose that it also keeps to a fast substratum there. That 

 Svedei.ius has not found it growing on the roots of the mangroves in Ceylon, I 

 think is due to the fact that the tide there is rather strong, so that the roots of 

 the mangroves are laid dry for a long time, a condition Caulerpa verticillata can 

 not live under. Svedei.ius also mentions expressly that it does not grow higher up 

 than to the low water mark. That Caulerpa verticillata by means of this mud- 

 collecting ability, which it has in common with the great part of the many richly 

 ramified algæ we find on the mangrove roots, has no little importance in the 

 accumulation of land in the lagoons, I need only just mention here. 



(2) Sand and mud Caul er pas. On sand bottom often more or less 

 mixed with mud, and on gravel bottom, we find several different species creeping 

 on the loose bottom. In shallow water e. g., I have found Caulerpa cupressoides 

 in several forms, Caulerpa crassifolia, Caulerpa racemosa var. lœtevirens, Caulerpa 

 sertularioides and Caulerpa taxi folia; in deeper water Caulerpa Ashmeadi, Caulerpa 

 proliféra, C. racemosa var. Lanwurouxii and different forms of C. cupressoides. By 

 means of their usually vigorous rhizomes these species often grow far and wide 

 over the loose and often soft bottom, and often form extensive growths sometimes 

 of a single species sometimes also of mixed species. The rhizome is as mentioned 

 vigorous, often with a pointed front end with which it can easily bore its way 

 through the sand. The most characteristic sand Caulerpa is C. cupressoides, which 

 especially reminds one of certain dune plants e. g. Carex arenaria, as I have pointed 

 out in earlier papers (7, p. 4, 5, p. 54). With its nearly awl-shaped end of the 

 rhizome it bores its way through the sand, and the often more than 1 meter long 

 rhizomes, which are straight as a line and from which at short distances the erect 

 assimilators grow up over the sand bottom, are in a sort of way like those in 

 Carex arenaria. 



From the rhizome at about the same distance from one another as the erect 

 shoots, vigorous roots grow down in the sand; these roots are at first undivided 

 but in a depth of about 2 — 3 cm. they divide up into numerous fine rhizoids to 

 which sand and gravel are fastened, in such a way that one commonly when 

 taking the plant up from the bottom, gets a whole clump of this material pasted 

 together. Compare for example the figures 9, 12, 16, 17, 18. Quite the same way 

 of fastening themselves is found also in other algæ e. g. Penicillus, Halimeda and 

 Udotea growing in this loose bottom (5, p. 54); it must be said to be an excellent 

 method of fixing the plant in the loose bottom, to knit the loose material together 

 in such a way that it can replace a fixed substratum. As I have mentioned earlier 



1). K. D.VIdensU. SelsU. Skr-, 7, Hæklie, natuivldcnsU, o(( malhcm AW. IV. ;'>. 45 



