94 CEYLON MARINE BIOLOGICAL REPORTS. 



But in this connection we need only refer to the parallel between C. clavifera, C. uvifera, and their 

 forms on the one side, and C. nummularia , peltata, and 'parvula on the other, to prove that Reinke's 

 assertion cannot be justified, for the " Spezies-character " in the former group is the ball-shape of the 

 small assimilation branches, in the latter their more or less disciform shape. But the " Anpassungs- 

 charactere," on the other hand, are the different lengths of the rhizomes and axes which form the 

 analogy between C. clavifera-nummularia andC. uvifera- peltata. And between them as a transition form, 

 or rather as a primary form common to both, stands C. Chemnitzia, which in its organization shows a 

 faculty to develop in the one or the other direction, thus less markedly differentiated or adapted than 

 the other two groups. 



If what Reestke says about Caulerpa were really a fact, it would be most remarkable and would 

 alone justify these algae in taking an exceptional place in the vegetable kingdom. For the opinion of 

 the biologists of our day is inclined to recognize that it is justifiable to distinguish between organization 

 characters and adaptational characters. So, for instance, Professor Gobbel said in his lecture at the 

 Congress of Arts and Sciences in St. Louis, 1904, "The Fundamental Problems of Present Day Plant 

 Morphology " {' Science ' N. S., Vol. XXII. No. 550, 1905): " In reality itseems to me that morphological 

 comparison as well as experiment shows that the distinction between organization and adaptational 

 characters is jiwtified." This principle may be said to hold good, as I have tried to show, also of the 

 many changing forms of the genus Caulerpa. 



III.— ON THE DIFFERENT KINDS OF VARIATION IN CAULERPA. 



1. Continuous Variations in Shoot Branchlets (PiNNUiiBs) from Base to Point 



The variations often point to a surface increase, — Comparison with the heterophylly of the higher plants. 



In the foregoing I have shown the differences in the organization and structure in the shoots of 

 Caulerpa, which are to be looked upon as adaptations to different modes of life. Thus we have seen that 

 the shoot systems of many surface living Caulerpas are closely connected with the conditions of the light 

 and the exposure to sea and wind that exist in the littoral region, and that when the Caulerpas grow 

 in deeper and calmer water they assume other larger and more branched and taller forms. In all these 

 cases the relation between organization and locality is evident. 



But in this genus there is another kind of variation in the shoots, between the forms of which and 

 the external conditions of the plant no such direct relation can be traced. It is the multitude of these 

 variations that seems to have caused the difficulties in determining the definitions and limitations of the 

 species in this genus. That Madame Weber v. Bosse has kept in sight these different variation tjrpes 

 can be seen from what she says on p. 245 in the " Monographic des Caulerpas: " "La question sur la valeur 



des especes est d'autant plus difficile a resoudre puisque le thalle a structure continue de ces algues, 



giibit une grande influence du milieu oii il pousse, et que la meme plante adopte en outre des formes 

 tres diverges, sans qu'on puisse trouver une raison quelconque pour expliquer I'apparition de formes si 

 varices au meme stolon." It is precisely this variation that has been so sharply accentuated, both by 

 Madame Weber v. Bosse and by Professor Reinke, that the variations according to localities have been 

 almost entirely overlooked. 



The variations that are not directly dependent on locality are mentioned by Madame Weber V. 

 Bosse on p. 246, and are either characterized by the branclilets or pinnules of an assimilator being of a 

 different form at the base than at the point, or there shoot out from the same horizontal axis dissimilar 

 assimilators, in that some have exclusively one kind, other exclusively another kind of branchlets. Last- 

 ly the variation can also consist in the branchlets being arranged in a varying number of rows, though 

 the branchlets be similar among themsslves. 



