6] FOUNDATIONS OF MODERN DISTRIBUTIONS 163 



out of an ice-cap, for on such mountains much perglacial persistence 

 is supposed by some students to have taken place. 



To begin with, much of the supposed evidence brought forward 

 for survival, such as the ' relict ' nature of particular plants in 

 particular areas, has proved to be either capable of other interpretation 

 or actually erroneous. Thus, geologists have insisted that several 

 of the areas claimed by the advocates of persistence to have been 

 ' refugia ' during the Pleistocene, were in fact glaciated. ^loreover, 

 latterly there have been numerous instances of plants of supposed 

 isolation or disrupted distribution (which were claimed to indicate 

 such refugia) being found in intermediate positions — sometimes even 

 on islands that ha\ e only recently risen out of the sea. Nor does 

 endemism (restriction to particular geographical areas) necessarily 

 indicate isolation and persistence ; it sometimes actually suggests 

 the opposite, as in some cases of hybrid origin ! 



It is noticeable that many of the isolated or restricted (endemic) 

 species, which are made so much of by advocates of the nunatak 

 hypothesis, are characteristic of, or sometimes restricted to, cal- 

 careous soils. It has been strongly counter-claimed that their spotty 

 or localized occurrence can best be correlated with soil characteristics, 

 the presence or absence of signs of recent glaciation being of little 

 or no consequence. And when we remember that many of these 

 are far-northern plants which favour ' open ' soils where competition 

 is lacking, and that in boreal regions calcareous areas are notable 

 for their poor vegetation but diversified flora, other possibilities 

 spring to mind and the nunatak hvpothesis becomes less and less 

 attractive. 



There are also objections to the nunatak hypothesis on the ground 

 of far easier and wider dispersal than its adherents will admit — for 

 example by Birds, and as regards characters of higher plants trans- 

 ported in pollen, and through airborne disseminules of lower plants. 

 Thus in the manner of plants. Birds also have their habitat pre- 

 ferences, often traversing great distances from one to another similar 

 spot. Although normally they are supposed to ' fly clean ' when 

 on migration, they must surely (as already mentioned in Chapter IV) 

 sometimes carry materials frozen or otherwise stuck to their plumage, 

 etc. — especially if flushed unexpectedly or unwell, w^hen they are 

 apt to ' neglect their toilet '. Pungent instances seem to be afforded 

 by the seeds, coated in protective regurgitate, that have been found 

 adhering to migrant Birds on the subantarctic Macquarie Island, 

 but apparentlv do not belong to any of the local species, as noted 



