252 PROCEEDINGS OF SECTION D. 



fact of the peculiarly close relationship of the deciduous Beeches 

 of Tasmania and South America. 



The genus Fagus consists of two or three deciduous trees of 

 northern temperate regions and about seventeen species, mostly 

 evergreen, found in Australia, Tasmania, New Zealand, and Fuegia. 

 The southern species have smaller flowers and very narrow medul- 

 lary rays, otherwise there is little to warrant their being considered 

 generically distinct ; but, however that may be, we cannot do other- 

 wise than accept their close relationship, which means, that the 

 groups were once continuous across the equator. There is one point 

 in favour of a polar migration, and that is the deciduous habit of 

 one Tasmanian and three Fuegian species. The shedding of the 

 entire foliage at a stated period of the year is generally ascribed 

 to be an adaption to xerophytic conditions. We know this to be 

 the case in countries with a periodic dry season, and have generally 

 concluded the physiologically dry condition of frozen ground in 

 high latitudes to be sufficient reason for the evolution of a deciduous 

 habit in circumpolar regions. But here probably another factor 

 has had influence, namely, the absence of light for some months at 

 a time. The retention of foliage by a tree condemned to periods 

 of half-yearly starvation is a distinct disadvantage. There is 

 nothing in the climate of Tasmania and Fuegia to render the 

 decidvious habit a benefit, wherefor these trees may with some 

 probability be assumed to have acquired the habit while living on 

 land much nearer the pole. The Tasmanian deciduous Beech 

 appears to be senile. It develops reproductive organs with fair 

 profusion, also quantities of barren nuts, seldom good ones. A 

 further link of attachment of the Tasmanian and Fuegian Fagi to 

 the exclusion of those of New Zealand may be found in the presence 

 of almost identical parasitic Cyttarias in both places. Seeds do not 

 float for a great length of time, and do not maintain their germina- 

 tive capacity after a short submergence in sea water, also the topo- 

 graphy of the southern portion of the globe would require the pro- 

 foundest modification to produce a sufficiently rapid current between 

 Tasmania and Fuegia. It is inconceivable that these Fagi can have 

 been transported by oceanic currents, and quite impossible that the 

 parasitic Cyttaria can have been carried in conjunction unless it 

 can be proved that it perennates in the ovule. The life history of 

 this fungus has not been worked out, but what we know of it points 

 to a localised infection and habitation. It appears on the axis 

 where it fruits year after year on the same spot, the vegetating 

 growth inducing hypertrophied knobs often attaining a large size. 

 If its apparent habit is the real one indicating it a wound parasitic, 

 then it can only have migrated with its host along a continuity of 

 land. Whether this continuity was from a cooler equatorial condi- 

 tion till the ultimate habitats of Fuegia and Tasmania were reached, 

 or whether the last phases of habitation are vestiges of a polar 

 continent, appears the question to be decided. The fixed deciduous 

 habit of some species appear to favour the latter conclusion. The 

 presence in Tasmania of a Drimys, an Oiirisia, Prionotes, Nertera, 



