Ecological and systematic studies of Ecological and systematic studies of the Ceylon species of Caulerpa ecologicalsystem00unse Year: 1906 132 CEYLON MARINE BI0L0C4ICAL REPORTS. increase in size. Moreover the side axes have a pronounced tendency to develop their disciform branchlets on one side only, on the upper side ; which apparently depends on their position in relation to the horizontal level. For, horizontal axes form their assimilation system only on the upper side, vertical ones all round, which is natural from the point of view of their exposure to the Ught of most advantage to
Ecological and systematic studies of Ecological and systematic studies of the Ceylon species of Caulerpa ecologicalsystem00unse Year: 1906 132 CEYLON MARINE BI0L0C4ICAL REPORTS. increase in size. Moreover the side axes have a pronounced tendency to develop their disciform branchlets on one side only, on the upper side ; which apparently depends on their position in relation to the horizontal level. For, horizontal axes form their assimilation system only on the upper side, vertical ones all round, which is natural from the point of view of their exposure to the Ught of most advantage to them ; this is especially the case if these horizontal axes take root. A transition to C. nummularia is thus effected, since, as I will show later on, it is just this form that is characterized by its assimilation discs being one-sidedly developed on the horizontal procumbent main axis. Also in another respect this form is remarkable in that, as fig. 33 shows, some of the disciform assim- ilation branchlets are somewhat swollen and thus would very closely remind one of c?aw/era branches, if a rather evident border did not give evidence of the branchlets having originally been flat (fig. 34). Weber v. BossE mentions about C. macrodisca (Agardh), that its great branchlets are ' distinctementbombes dans lean pour devenir bientot plates quand ils en ont ete retires.' While then in the case of C. macro, disca it seems to be the rule, in peltata it is rather the exception, the majority of the branchlets having qiute flat assimilation discs. It is to be noted that C. nummularia, too, seems to have the same tendency. So Harvey's Friendly Island No. 76 (Herb. J. G. Agardh, 16814), very evidently shows a mixture of nummula- ria and davifera branches. This form Harvey has called G. clavifera v. platijdisca. Fig. 34.—C. peltata (lam.) f. ad claviferam, swollen branchlets from the upper part of an axis. (3 X 1). Fig. 33.—V. peltata (lam.) 1'. ad claviferani (1 X 1). Oeographical dist
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