VIII LITTORAL PLANTS AND CURRENTS OF THE PACIFIC 65 



he designates nine only as exclusively dispersed by the currents. 

 Even this list, in one respect, needs correction (see Note 33) ; but 

 it is of interest to note that this eminent botanist from the first 

 never looked upon the agency of the currents as a very important 

 factor in plant-dispersal ; and, finding in the specially directed and 

 carefully performed experiments of Thuret confirmation of his 

 views, he reiterated his opinion in a note to that author's paper in 

 1873 (cited in Chapter III.). 



However, De Candolle was quite right in minimising the effect 

 of currents on the distribution of plants. His extensive survey of 

 the plant-world from the standpoint of dispersal gave him that 

 sense of proportion in assigning values to dispersing agents which 

 enabled him. to feel his way almost intuitively, even where exact 

 data were often lacking. It is, however, a little disappointing to 

 find such a slight treatment of the subject in Kerner's great work 

 on the Natural History of Plants, though one can scarcely con- 

 trovert his opinion that the dispersion of plants, as a whole, is not 

 appreciably affected by this process. Numerically speaking, this 

 is in the main correct ; yet it is here that the genius of Schimper 

 led him to recognise and to mark out a line of investigation, fruit- 

 ful in important results, in connection with the weighty question 

 of" Adaptation." If the author of this work has been able to add 

 a little to our acquaintance with this subject, he owes much to the 

 inspiration he received from Schimper's memoir on the Indo- 

 Malayan Strand-Flora. 



Still, it must be admitted that the effectual operations of the 

 currents as plant-dispersers are limited to the shore-plants with 

 buoyant seeds or fruits. If we were to include in our list the 

 shore-plants of temperate regions that possess seeds or fruits 

 capable of floating in sea-water for long periods, and of afterwards 

 germinating, the total for the whole world would not, I imagine,, 

 reach 200. We cannot here concern ourselves with those purely 

 river-side plants that contribute their buoyant seeds and seed- 

 vessels to river-drift, since there is no evidence indicating that river- 

 side plants are effectively dispersed by the currents unless they 

 also frequent the estuary and the coast-swamp ; and in that case 

 they come under the head of littoral plants. The total for the 

 whole British flora would probably not far exceed a dozen, and 

 nearly all of them are very widely dispersed. 



The working value of the currents as plant-dispersers in the 

 Pacific can be rudely estimated by the number of littoral plants 

 with buoyant seeds or fruits that occur in the various groups. 



