118 NOTICES OF BOOKS. 



have seeds that ouly ripen under water and sink ^ others liave seeds 

 that present no facilities for transport by winds, cannot have been in- 

 trodnced by man, and will not endnre exposure to salt-water,* 



Forbest 



6. Certain countries, separated by wide expanses of ocean, have 

 more sj^ecies in common than either the distance or nature of these 



r 



climates would render probable under ordinary circumstances ; whilst 

 contiguous countries, w^ith similar climates, sometimes present very dif- 

 ferent species. 



7- Some countries are remarkable for the great number of species 

 they contain in a small area, others for comparative poverty. 



8. Species of simple structure have often wide ranges, though their 

 seeds are not well adapted for transport ; on the' other hand, many 

 species, whose seeds appear perfectly adapted to secure a wide distri- 

 bution, have very narrow ranges. 



All these phenomena direct the attention of the inquirer to a different 

 order of things to that now existing ; that is, to a former epoch, namely, 

 to the quaternary-}- period of geologists, if not to a still earlier date in 

 the world's history. Mention is made of the late Professor E. 

 as the strenuous supporter of this view. 



Under the head of proofs of the historical antiqnity and indications 

 of the geological antiquity of the greater part of existing species, M. 

 de Candolle boldly states that this can be demonstrated both a priori 

 and by some observations of geologists. Under the a priori, he alludes 



r 



* :Mr. Darwin's experiments on the power which seeds have of retaining their 

 vitality when exposed to the eifects of salt-water (Gardeners' Chronicle, 1854-5) 

 were of course unknown to M. de Candolle, 



t The Post-pleioccne of Enghsh geologists, or that immediately preceding the 

 present. 



X M. de Candolle mentions the opinions of Forhes, given in his well-known Essay, 

 as ingeuioiis hypotheses concerning one region of the globe only, and applicable only 

 to a part of the pheaomena to which his book is devoted; and he professes to 

 take a more general view, to examine the foundations of the hypothesis, to discuss 

 its probability, and to compare it with other theories. M. de Candolle here perhaps 

 hardly recognizes sufficieutly the real valne of Torbes's Essay^ and that the evidences of 

 the probable truth of the hypotheses he advocates rest upon geological and zoological 

 facts ; for though a vast number of difficult phenomena in the geographical distribu- 

 tion of plants, cited by Forbes, De Candolle, and others, may be explained by the 

 hypothesis, none of these can be said to afford anything approachiui^ to proof of it. 

 Forbes had animals and shells, both in a recent and fossil state, to reason from, oc- 

 cupying in part the areas now occujned by the plants now existing, and in part also 

 ancient rocks, whose geological relations were not ouly well knoWu, but the theory of 

 whose formation is proved. These points are however fully admitted at the conclu- 

 sion of the volume. 



