156 NOTICES OF BOOKS. 



origia for each. species have admitted a simultaneous creation, if not of 

 the whole world, at least of all vegetables, and of all animals bat man, 

 and in doing so they have lost sight of the fact that some plants are 

 parasitic on others, and some require the shade of others. 



The strongest objection however to the creation of single individuals 

 is, in M. de Candolle^s opinion, the disconnected species alluded to at 

 p. 116, whose individuals he supposes to have originated at the spots 

 where they arc now found, or at any rate at localities nearer to those 

 spots than they are to one another. 



Under the head of Duration of Species and of Eaces, the subject of 

 their disappearance is discussed ; the absolute extinction of them M. 

 de CandoUe appears to think is sometimes too hastily assumed, because 

 relays of seeds lie buried in the soil, etcf 



Chapter ^'i. On the Geographical Habitats of Genera: the Limits 

 and Form of their Habitats. 



In the preliminary discussion of M. de CandoUe maintains the view 

 which he has always held (in opposition to the majority of botanists) 

 that genera are even more naturally limited groups than species. | the 



* The . admission of many centres of creation for each species opens the door to 

 the admission of many other hypotheses, ail tending to disprove the permanent dis- 

 tinction of species ; for instance, if species are created at two different spots, tney 

 will, it is only reasonahle to suppose, appear in many cases as two races , and if m 

 many spots, we' may have as many races originally created, whence race and species 

 become practically convei-tible terms from the very beginning of the creation of the 

 species. Again, if species are successively created, why may not individuals of the 

 species be also ? and if this be granted, the subject of distribution is hopelessly com- 

 plicated. To the progress of modem geology such admissions are fatal. 



t The possibility of species being thus preserved when to all appearance lost is 

 no dcubt true; but in reality it is not worth alluding to as a conservative agent of 

 any appreciable effect. M. de CandoUe alludes to it especially in reference to the 

 asserted extinction of St. Helena species. The forests of this islet (extending oyer 

 several thousand acres) were, it is well known, destroyed, and with them a native 

 vegetation that may fairly be assumed to have numbered several hundred species. 

 Of thig native vegetation now very few species remain, and these are either con- 

 fined to places where the forest w^as not destroyed, or are plants that grew where 

 it never existed. If the seeds of the others had remained alive iu the soil, there 

 would surely have been some renovation of the vegetation from the old ; but there 

 has been none. Since the island was first botanized, half a century ago, no new plant 

 has appeared on it, and every old one, without exception, is getting rarer ; some of 

 them indeed have become tottdly extinct. Hundreds of acres of St. Helena soil arc 

 disturbed for gardens, plantations, and agricultural operations, and numberless oppor- 

 tunities are thus given for any buried seeds to grow and flourish, but nothing of the 

 kind has ever taken place. The wild plants of the remaining woods, and the trees 

 forming those woods, do not even spread into the artificial shrubberies and planta- 

 tions on whose outskirts they arc abundant. 



% In this opinion we do not agree ; neither do we admit the premises from which 

 M. de CandoUe draws his conclusions, as that an intelligent observer who is uo 



