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A General Consideration of the Suba'erial and Fresh-water Algal 

 Flora of Ceylon. A Contribution to the Study of Tropical 

 Algal Ecology. Part I. — Suba'erial Algce and Algce of the 

 Inland Fresh-waters. 



By F. E. Fritsch, D.Sc, Ph.D., F.L.S., Assistant Professor of Botany, 

 University of London, University College. 



(Communicated by Professor F. W. Oliver, F.R.S., — Received June 26, — Read 

 November 1, 1906, — Received in revised form, January 2, 1907.) 



Introducto ry Remarks. 



During the year 1902 I was occupied with a study of the algal flora in the 

 hot-houses of the Royal Botanic Gardens at Kew, and certain observations 

 made then seemed scarcely to support the prevalent view of the very close 

 .similarity between tropical and temperate algal vegetation. This stimulated 

 me to undertake a personal investigation of some tropical algal flora, and 

 Ceylon was chosen owing to the diversity of climatic conditions which it 

 presents. My object was rather to study the ecological and biological aspects 

 of the algal vegetation than to make a systematic collection of materials for a 

 flora, and I hope to be able to show that I have been in some measure 

 successful. A careful analysis, as I think the subsequent pages of this paper 

 will show, brings to light very considerable differences between algal growth 

 in the tropics and in our parts, although a certain similarity between fresh- 

 water Alga? all over the surface of the earth (considerably greater than in the 

 case of the terrestrial flora) is indisputable. It is, in fact, a natural 

 consequence of the uniform character of the surrounding medium. 



The island of Ceylon is peculiarly favourable for a study of the influence of 

 tropical temperature and moisture on the distribution of algal growth, since 

 the rainfall varies considerably in different parts of the island, while the 

 mountainous southern portion (attaining a height of 8000 feet and more) 

 produces a very considerable range of temperature, from the intense heat of 

 Colombo and other lowland places to the high-lying Nuwara Eliya, where, at 

 certain times of the year, the thermometer falls to below freezing point at 

 night. In fact, we have here confined in a narrow compass almost all the 

 different possibilities that can be realised in the tropics. It may be well at 

 this point to briefly outline the range of variation in this respect (see also 

 the map). The low country, with its high tropical temperature, shows great 

 diversity in the amount of rainfall ; so that some localities are exceptionally 



