S46 president's address. 



time connected with the warm seas of Europe and Southern Asia. 

 The author argues for a gradual cooling down of the sun as 

 l)r()(Iucing all the phenomena observable. The sun is now in the 

 con lition of a yellow star ; all through the Palaeozoic, Mesozoic 

 and part of the Tertiary it was a white star, thus the heat con- 

 ditions were more intense; and although the tropics need not have 

 been hotter, the heat would be better distributed towards the 

 poles. He points to the more ancient types of plants and 

 animals (reptiles) as requiring warmer conditions, while warm 

 blooded mammalia and birds are adapted to the cooler conditions 

 now prevailing. 



As a rule every writer looks to his own theory as being all- 

 sufficient, whereas probably there has been a combination of 

 conditions producing the effects, so that not only may we conclude 

 that the reduction of the sun's radiating power may have had much 

 to do with the present less favourable conditions, but that some 

 of the intermediate changes may have been contributed to by 

 various causes — namely, small shiftings in the geographical 

 position of the earth's axis, increase in the eccentricity of the 

 orbit, to some extent by an alteration of the distribution of land 

 and water and the induced air and ocean currents, and also by 

 cosmical causes and intercepting of the sun's heat b}- diffused inter- 

 .stellar matter. 



IxsuLAR Floras and Oceanic Islands. 



This subject is one the consideration of which cannot be 

 separated from that of the permanence of oceanic beds. 



Wallace divides islands into three classes : — Recent continental 

 islands, ancient continental islands and oceanic islands, the latter 

 being generally understood to be those surrounded by seas of 

 more than 1000 fathoms, although as an exception it is acknow- 

 ledged that some islands belong to the continental classes not- 

 withstanding that the ocean barrier is now over 1000 fathoms. I 

 think that Wallace scarcely sufficiently allows for the effect of 

 long periods of time in altering depths. Time may be all that is 



