NOTICES OF BOOKS- 155 



from another who considers that twice ten times that number of spe- 

 cies should be maintained. M. de CandoUe also shows that the degree 

 of variability of the genera is to a great extent in direct proportion to 

 the antiquity M. Lecoq assigns to them, and in which relative scale 

 of antiquity M. de CandoUe agrees, namely, that the oldest are Cryp- 

 togams, next Monocotyledons, and lastly Dicotyledons. 



The purely hypothetical question of the origin of existing species is 

 remarkably well treated, and is also illustrated as fully as it is capable 

 of being, which however is not saying much. The first (or the several 

 first) organic beings were either elaborated from inorganic matter in 

 accordance with some physical law unknown to us, or they were created 

 out of nothing, or out of inorganic matter, by a higher power not 

 residing in matter (" par une cause superieure etrangere a la nature"). 

 Each of these hypotheses, he adds, demands a something which we 

 can neither see, feel, nor even comprehend. 



Some naturalists have sought to escape the difficulty, says M. de 

 Candolle, by the doctrine of progressive development, an hypoth 

 which does not do away with the necessity of a supernatural cause to 

 account for the origin of species ; to which he adds, that this is a sub- 

 ject upon which we know nothing. It marks the boundary between a 

 science of observation and one of speculation ; it however branches off 

 into three others which are more capable of study. 



1. On the primitive centres of vegetation he arrives at three conclu- 

 sions :— that the region in which a species originated cannot be exactly 

 determined ; that species have originated at numerous different regions ; 

 that some of these regions may be indicated with a certain degree of 

 probability, but not with precision, on account of the interchange of 

 species and the probable disappearance of some of the regions. 



2. The creation of species has probably been successive. This all 

 existing facts in both geology and botany tend to show. 



3. With regard to the hypotheses that species are created as smgle m- 

 dividuals or in'single pairs, or that many individuals of each were created 

 at once, the former appears to M. de Candolle to be too seductive from 

 its simplicity, and adds that it has led many authors mto a palpable 

 contradiction. He says that almost all the advocates* of a single 



opinion does not prevail. After aU, it may uciuahu . *^.^,_,_ ^*4...x..a n...?,...« 



misletoe 



trc€ rather than of its bccd 



