S2 CEYLOX MARINE BIOLOGICAI. in>:PORTS. 



banks in the Gulf of Mannar, and for that J am also indebted to Mi. Hokxell, who collected i( dmiug 

 his official journeys for the study of pearl oysters. 



Important sources for studies in the marine flora of Ceylon are the collections of Harvey and 

 Ferguson. W. H. Harvey stayed in Ceylon from September to December, 1853, and visited Trinco- 

 malee, Weligama, and Galle. Of his collections, wliich are preserved in Trinity College, Dublin, there 

 are duplicates in the collections of the Royal Riksmuseum in Stockholm and in the Algal Herbarium 

 of J. G. Agardh in Lund. The rich collections of marine algse made by W. Ferguson are preserved 

 in the British Museum, but duplicates of them are also in the Herbarium at Peradeniya and in the Her- 

 barium of J. G. Agardh in Lund. Through the courtesy of Dr. J. C. Wiixis, Director of the Botanic 

 Gardens. Ceylon, the Fergxjson collections in the Peradeniya Herbarium were placed at my dis- 

 posal at Uppsala, and this considerably assisted me in my studies. I am deeply indebted to Dr. Willis 

 for tliis material help. From the Botanical Museum of Copenhagen and from the Botanical Department 

 of the Royal Riksmuseum in Stockholm I was also allowed to borrow ricli collections of Caulerpas, which 

 were kindly lent me as material for comparison, and for which I here beg to thanli the Directors of those 

 Institutions, Professor E. Warming and Professor C. A. M. Lindman. Finally, I beg to express my 

 thanks to Professors 0. Nordstedt, B. Jonsson, and S. Murbeck in Lund for their kind assistance 

 during my studies in J. G. Agardh's valuable Algal Herbarium in the same town. 



The extent of my material has forced me to publish my studies in several parts, and if I begin 

 with Caulerpa it is because the plants of this genus, interesting from so many different points of view, have 

 hitherto been studied so little in their natural state from an ecological point of view — i.e., their biology. 

 Hence it seemed to me that a real gap in our knowledge of these interesting plants remained to be filled, and 

 that this should be done as soon as possible. It is clear that a study of this nature introduces such 

 difficult questions as the relationship and variation of the species, their geographical distribution, and 

 the like. To try to give an account of the Ceylon Caulei-pas from these points of view is the aim of the 

 present essay. 



Uppsala, April, 1906. 



II.— ON THE MODE OF LIFE OF THE CAULERPAS. 



T/ic Relation betwep.n Habitat and Orqanization. — Do Caulerpas show any Examples of AdapfMimi ? 



1. — Do all Caulerpas grow under similar External Conditions ? 



Concerning the ecology of the Caulerpas, there are in botanical literature very few, indeed practically 

 no reports. This may be chiefly attributed to the fact that so many of those who have studied the 

 tropical algse had no opportunity themselves of observing them in nature, but examined them exclusively 

 from material collected by others. Tims, for instance, C. A. Agardh and J. G. Agardh, who were the 

 first to give a detailed monographical account of the genus Caulerpa, had themselves never collected 

 or even seen any living Caulerpas. 



On the other hand also, the algologists who, as Harvey, had themselves travelled and collected 

 much, only devoted themselves casually to the observation of the habitats of the algae, of which, as 

 a rule, only short notices were communicated. 



Of tliose who, more recently, have dealt with the Caulerpas monographically, Madame Weber 

 V. Bos.se and Professor Rbinke, only the former had collected her material herself , during travels in the 

 Tropics ; but still it is remarkable how entirely her great work, " Monographie des Caulerpes," is lacking 

 in information about the habitats, vertical distribution, &c., of the different species. Hence, too, it is 

 fully explicable that Professor Reinke, in his discussion of the Caulerpas, almost starts a priori horn 

 the assumption that they all live under practically quite similar circumstances. Thus, in speakino 

 of the problem of the surprising diversity of the organisms (" Ueber Caulerpa," pp. .5.5, 88 ), he mentions 



