INTRODUCTION TO THE GHLOROPHYGE^ PART 



My studies on the marine algae of the Danish West ladies are based" 

 upon the collections 1 have gathered there during my three visits to the 

 islands in 1892 (February — March), 1895 — 96 (December— ^January) and 

 1905 — 06 (end of December to beginning of April). 



The reason for my not being able to work up my collections before 

 now is, that my examination of the algal vegetation of the Faeroes was 

 begun in 1895 and it was not until I had finished this that I could devote 

 myself to the study of the West Indian Algae. 



In this first part comprising the Chlorophycese I give a survey over the 

 species, which I have so far found in my gatherings. 



In several papers published earlier I have already dealt with some 

 groups of the Chlorophycese. These papers are: 



Contributions it, la connaissance du genre Siphonocladus Schmitz (Oversigt over det kgl. 

 danske Videnskab. Selskabs Forhandl., 1905, Nr. 3). 



An ecological and systematic account of the Caulerpas of the Danish West Indies (Kgl. 

 Danske Videnskabernes Seiskabs Skrifter, 7. Rsekke, naturv. og mathem. Afd. IV. 5, 1907). 



The species of Avrainvijlcas hitherto found on the shores of the Danish West Indies (Viden- 

 skab. Meddelelser fra den naturh. Foren. i Kobenhavn, 1908). 



The Dasyeladaceae of the Danish West Indies. (Botanisk Tidsskrift, 28. Bind, Kdbenhavn, 

 1908). 



Some Chlorophycese from the Danish West Indies, I. (Botanisk Tidsskrift, ."^l. Bind, Koben- 

 havn 1911). 



Some Chlorophycese from the Danisk West Indies, II. (Botanisk Tidsskrift, 32. Bind, Koben- 

 havn 1912). 



For the sake of completeness I give again here the contents of these 

 papers though in somewhat shortened or sometimes also somewhat altered 

 form. 



Compared with the chlorophyceous algal flora in northern waters that 

 found at the islands here in the tropical sea has proved to be very rich in 

 forms, much richer than those in the temperate and cold seas. To be sure 

 some forms are wanting here, thus it is remarkable that e. g. UlothrLr, so 

 common in northern seas, has not been found, but on the other hand 

 several families are represented which are not at all found or only with a 

 single representative in the northern waters. 



And while in the northern seas the Chlorophycese with the exception 

 of the Ulvacese and some forms of Cladophoracese are not of much impor- 

 tance as regards the copiousness of the vegetation, in the tropics the 

 Chlorophycese are of great significance and this applies not only to the 

 above-mentioned Ulvacese and Cladophoracese, which at the shores of the 

 Danish West Indies are often abundantly developed, but especially to 

 representatives of the three families: Codiacese, V aloniacese and Caulerpacese. 

 These which are quite or nearly absent in northern seas, are here in the 

 tropics luxuriantly developed arid represented by a great number of forms. 

 And by the ability of many of these species to grow in loose, sandy or 

 muddy bottom, being often present in enormous masses there, they also 

 contribute greatly to the luxuriance of the vegetation. 



As another difl'erence from the northern seas I may also point out 

 that while in the tropics several of the Chlorophycese are able to grow 

 abundantly even at a depth of about 20 fathoms, in the northern seas, in 



U^o"^ 



