xxxiii SEED-DISPERSAL AND GEOLOGICAL TIME 511 



he find any seeds, namely, in the case of a snow-bunting which 

 carried, attached to its plumage, an achene of, perhaps, a 

 Ranunculus, and in its gizzard a seed like that of a Suaeda. My 

 discovery of a small, hard seed in the gizzard of a Cape-pigeon 

 (Daption capensis) 550 miles east of Tristan da Cunha has been 

 referred to by Mr. Hemsley in his introduction to the Botany of the 

 ''Challenger" Expedition (p. 45). On p. 188 I have mentioned 

 the probable dispersal of the seeds of Caesalpinia by frigate-birds 

 and boobies ; and in Note 59 reference is made to some large 

 seeds found in the crop of the Fulmar petrel. 



Gulls, when they nest at the coast, where the sea-thrift 

 (Armeria vulgaris) and the sea-campion (Silene maritima) thrive, 

 or inland amongst the heather-covered slopes, must often carry the 

 seeds of these plants from place to place in their plumage (see 

 Notes 15 and 16); but, as shown below, they can also disperse 

 plants with fleshy fruits which at times form their food. Gulls, 

 geese, and arctic grouse take an important part in the dispersal of 

 seeds in the cold latitudes of the northern hemisphere ; and few 

 things are more suggestive in this way to the student of 

 distribution than the data supplied by Ekstam, Hesselman, 

 Sernander, and others for the region including Spitzbergen, Nova 

 Zembla, and Arctic Norway. The history of the discussion 

 relating to the flora and fauna of Spitzbergen reproduces in its 

 main features the various stages in the controversy that has been 

 waged in connection with the Pacific islands. 



When Ekstam published, in 1895, the results of his observations 

 on the plants of Nova Zembla, he observed that he possessed no 

 data to show whether swimming and wading birds fed on berries ; 

 and he attached all importance to dispersal by winds. On subse- 

 quently visiting Spitzbergen he must have been at first inclined, 

 therefore, to the opinion of Nathorst, who, having found only a 

 solitary species of bird (a snow-sparrow) in that region, naturally 

 concluded that birds had been of no importance as agents in the 

 plant-stocking. However, Ekstam's opportunities were greater, 

 and he tells us that in the craws of six specimens of Lagopus 

 hyperboreus shot in Spitzbergen in August he found represented 

 almost 25 per cent, of the usual phanerogamic flora of that region, 

 in the form of fruits, seeds, bulbils, flower-buds, leaf-buds, &c. 

 This observer now also realised the importance of gulls and geese 

 in dispersing certain types of plants in those latitudes. Species of 

 Larus, he says, consume greedily all kinds of berries, and especially 

 those of Empetrum nigrum, the stones of which were found un- 



