512 A NATURALIST IN THE PACIFIC chap. 



injured in their droppings by Professor Lagerheim in Arctic 

 Norway. Geese, as we are also informed, are hearty plant-eaters 

 in Spitzbergen ; and Ekstam found in their droppings the fruits of 

 Oxyria digyna as well as an abundance of uninjured bulbils of 

 Polygonum viviparum, some of which proved to be capable of 

 growth (See Ekstam in Tromso Museums AarsJiefter, vols. i8 and 

 20, 1895-7). 



The result of Ekstam's observations in Spitzbergen was to 

 lead him to attach a very considerable importance in plant- 

 dispersal to the agency of birds ; and when in explanation of the 

 Scandinavian elements in the Spitzbergen flora he had to choose 

 between a former land connection and the agency of birds, he pre- 

 ferred the bird. 



I have gone into some detail in this matter because the Spitz- 

 bergen controversy in some respects might have equally centred 

 around New Zealand or some of the large continental islands of the 

 tropical Pacific. There is at first the endeavour in the absence 

 of precise knowledge to disregard the bird and to look for a land 

 connection. With the increase in our acquaintance with the 

 efficacy of bird-agency in seed distribution there is the abandon- 

 ment of such a view. In both localities, however, there are the 

 same counter-indications of the insect faunas, and the same 

 considerations are raised by the absence or presence of larger 

 animals in the regions concerned. The principal difference lies 

 in the frozen sea, and yet, strangely enough, it does not seem to 

 affect the problem much. It would indeed appear that the ques- 

 tions raised by the floras and faunas of the Pacific islands are not 

 peculiarly Pacific in their character ; and it is probable that the 

 difficulties here presented are repeated in one form or other in the 

 case of large islands over all the globe. 



On the efficacy of Ducks and other Waterfowl in the Distribution 

 of Aquatic Plants. — It is highly probable that aquatic plants, like the 

 beach plants distributed by the currents and the ferns and lycopods 

 distributed mainly by the winds, have changed much less in the 

 course of ages than the plants of the inland forest. This in all 

 three cases is chiefly due to the uninterrupted freedom of commu- 

 nication by means of the dispersing agency. 



Wild ducks and their kind are active agents in the distribution 

 of the seeds of aquatic plants ; but it is curious that the early 

 experiments of Caspary went far to discredit them in this respect. 

 As quoted by Dr. Schenck in his Die Biologic der Wassergewdchse, 

 1886, he fed tame ducks with the seeds of water-lilies and found 



