64 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 1P> 



sionally beyond T0° from the access of the great current from the 

 north, shows that corals do not require the amount of temperature 

 supposed by some authors. M. Couthouy expresses this idea, that 

 " Astrseas especially seem, in exposed places washed by the coral 

 breakers (at a temperature not over 78°), to find their most con- 

 genial climate*:" and Mr. Dana has shown that some species 

 grow in a temperature of 66°t. As the average temperature of Port 

 Jackson is lower than this, it is certain that some corals exist in a 

 considerably cooler climate than others. 



November 18, 1846. 



Professor L. D. B. Cordon of Glasgow was elected a Fellow of the 

 Society. 



The following communications were read : — 



1 . On the Laws of Development of Existing Vegetation and the ap- 

 plication of these laws to certain Geological Problems. By John 

 Walton, Esq. 



The author's remarks are chiefly founded on the excentrical position 

 of the pith of exogenous trees, which he states are caused by unequal 

 heat afforded to the north and south side. He supposes that a north 

 and south line drawn through the central axis in a transverse section 

 of a tree will generally bisect the section, while an east and west line 

 divides it into two unequal parts ; but that at the equator and poles 

 such section will be bisected by either line. 



He then alludes to the prevailing wind as a disturbing cause, not 

 however obliterating the action of the sun, and concludes that con- 

 temporaneous plants, whether fossil or not, being in their upright 

 position with their roots downwards, and having lines of like deve- 

 lopment parallel to each other, have grown in the place where they 

 are found and are in their original position. He also concludes that 

 if the lines of development are not parallel in beds of different ages, 

 the line of action of the cause of that development has changed. 

 He considers that many important geological conclusions may be 

 deduced by applying these propositions. 



The author next proceeds to the subject of internal heat, and con- 

 siders that since it would tend to produce an equality of develop- 

 ment, we may determine its former extent of action by examining 

 the trunks of exogenous trees. 



Although at first he only applied this theory to exogenous vege- 

 tables, he afterwards considered that the central pith of Stigraaria 

 and some other fossil coal plants sufficiently answered the conditions 

 of the problem, and thence has satisfied himself, that although the 

 data are not yet sufficient to base a definite argument upon, still 



* Boston Journal of Natural History, vol. iv- 

 t American Journal, vol. xlvi. p. 135. 



