368 W. A. Setchell — Classification and Geographical 



Cystoseireoe between New Zealand and the temperate seas of South 

 America. It, however, is the fact, that whilst this group literally 

 abounds in certain latitudes and longitudes, which are those of New 

 Holland and the west Pacific, they are nearly absent from analogous 

 positions in the longitude of South America." 



Besides the temperature of the water the temperature of the air 

 affects such species of algae as are partially or wholly exposed at 

 low water. This matter might affect the distribution of the kelps 

 to a slight extent,^ but most of them grow below low water mark. 

 Two other cavises, more local than general, which affect the distri- 

 bution of algse, are the nature of the bottom and the salinity of the 

 sea. Both of these are discussed by Kjellman in a very satisfactory 

 fashion.'^ The configuration of the coast, the amount of light, the 

 tides, etc., have their share in j^re venting or helping a form to get 

 a foothold on a particular coast but the main general factor is the 

 temperature of the sea. 



. As has been stated previously the kelps are inhabitants of the 

 colder waters' and decrease in numbers and luxuriance of growth as 

 we go towards the equator and cease, as a rule, long before we 

 approach either tropic. At the same time, they approach the poles 

 as near as the permanent ice will permit. They flourish in the 

 Arctic Oceans where the temperature even in summer is scarcely 

 above 0.0° C.,^ and they may fruit and produce germinating zoo- 

 spores at temperatures of — 1° to — 2° C.^ Prof. Kjellman, to 

 whose work on the " Arctic Algae " numerous references have been 

 made already, has had magnificent opportunities for studying this 

 subject in regard to the marine algae in general and has considered 

 the subject in detail in his published works. 



The Laminarieae, the Agareae, and the Alarieae belong among the 

 inhabitants of the very coldest waters. The Macrocystis is found 

 floating'' within 15° of the south pole and is abundant in the colder 

 Antarctic waters as a floating plant. The Macrocystis, however, in- 

 habits also the warmer waters and, as we shall see below, can endure 

 a range of temperature unknown in the case of any other kelp. 



1 Cf. Kjellman, Arctic Algse, p. 3 1 . 

 ^ Loc. cit., pp. 24 and 26. 



^ Kjellman, loc. cit., p. 15, ''The formation of Laminariacece is the best marked and 

 most widely distributed vegetation in the whole Arctic Sea," etc. 



4 Cf. Kjellman, loc. cit., pp. 31, 61, 84, etc. 



5 Cf. Kjellman, loc cit . pp. 82 and 84. 



6 Cf. Hooker, Flora Antarctica, Pt. 2, p. 465. 



