Laing. — On the Akjte of New Zealand. 305 



between them, and so are long reaches of sand and the 

 mouths of large rivers. As I have been unable to find any 

 observations on this matter in the books at my disposal, it 

 would, perhaps, be as well to illustrate these statements from 

 our New Zealand Algse. Amongst other species endemic to 

 the Chatham Islands is a very distiuct form of Landsburgia 

 (L. myricifolia, J. Ag.). It is a fucoid several feet in length, 

 and it must often, like L. quercifolia, be torn from the rocks 

 by the waves ; and yet, although it could almost certainly 

 survive a lengthened tossing on the ocean's surface, it has 

 been unable to establish itself on the mainland. It should, 

 perhaps, be pointed out that after the hold of the rhizoid has 

 been loosened, or when the plant — as generally happens with 

 some species — is broken off above it, there is, probably, no 

 possibility of its being able to affix itself again. At least, I 

 do not remember having seen a plant that had evidently once 

 been afloat re-establishing itself. It might, of course, although 

 it had been subjected to weeks of tossing on the ocean's 

 surface, go on producing spores, which might have a chance 

 of germinating if the plant were finally cast up on a rocky 

 shore. If a comparatively narrow arm of the sea can form a 

 barrier to a strong, coarse plant like this, much more so will 

 it be one to the delicate Bhodophycece. These plants soon 

 bleach and disintegrate under the influence of the sun's light 

 and heat when on the surface of the water, so that it is 

 extremely improbable that the smaller forms could cross in a 

 living condition a wide arm of the ocean ; and it is very im- 

 probable that even the larger forms could live for a lengthened 

 time on the surface of the sea. Moreover, as we shall 

 see presently, the facts of distribution do not by any means 

 favour the supposition that ocean-currents do distribute living 

 Alga3 broadcast on the shores which they wash. It is still 

 more difficult to imagine that oospores and carpospores 

 apart from the plant should be able to cross successfully 

 many miles of ocean. 



I do not wish for a moment to deny that oceanic currents 

 do sometimes determine the distribution of Algse. The most 

 notable example of this is perhaps to be seen in the case of 

 Macrocystis, which follows the cold antarctic current up the 

 western coast of South America, though not up the eastern 

 side. Here, however, it is the temperature of the current, 

 and not its direction, that determines the existence of the 

 species. There is, however, a method by which even delicate 

 species might in some cases be conveyed from shore to shore — 

 that is, as epiphytes. Macrocystis, for example, apparently 

 flourishes like the Sargasso weed in the open ocean.* If a plant 



* " Flora Antarctica," vol. ii., p. 465. 

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