NOTICES OF BOOKS. 189 



the widely different local conditions of many of the areas, and espe- 

 cially the presence of lofty mountains in some ; and secondly, the ex- 

 tremely different views taken by the authors of the several Floras, of 

 the value of specific characters. Thus^ Ledebour's estimate of the 

 Flora of Dahuria, Baikal, etc., at upwards of 1336 flowering plants, 

 is manifestly founded upon ideas of species which are totally incom- 

 patible with those of Beck, who estimates the Flora of the Northern 

 and Middle United States at 2125, or of Georgia and South Caro- 

 lina at 2158; and in general we may remark that the North Ame- 

 rican botanists take a much wider, and, we think, a more philoso- 

 phical view of the value of specific characters than many European 

 botanists do. We should also have preferred Watson's corrected esti- 

 mate of the real number of indigenous British plants, to that adopted, 

 which includes a number of plants whose claims to be considered 

 as species or as British nobody vindicates. On the other hand, any 

 comparisons founded on a collection of only 305 New Guinea plants 

 (an archipelago which must contain upwards of 3000), and in which 

 collection the Orckldea are almost five times more numerous than 

 the Eudiace^e, and three times more numerous than the Leguminosa^ 

 and in which 14 Orders, including Scitaminece, Sapotece, and Palms, all 

 appear as more numerous than the Composittey which latter Order has, 

 further, fewer than seven species, are manifestly adapted to mislead.* 



We do not mention these points as objections to the tables being 

 introduced, nor because we suppose M. de CandoUe to be ignorant of 



them, but because we consider that they are sources of greater inex- 

 actness in the method, and introduce graver errors into the results, 

 than those causes which, he says, render the inquiry into the rehtive 

 proportions of Dicotyledons and Monocotyledons almost useless. 



Under the head of the number of families in a country to which 

 half the species it contains belongs, the general law is given, that the 

 richer a Flora is in species, the greater the number of families which 

 must be enumerated, commencing with the largest, before half the 

 number of species is included ; in other words, the richer the Flora 

 the greater the number of Natural Orders. 



Chapter 23. On the comparison of diflFerent countries as regards their 



nioat characteristic Natural Families. 



* In another place we find it stated without a qualification that the Orehidea Umn 

 sixteen per cent, of the Flora of New Gninca ; and the OmiposUa fifteen iKjr cent, of 

 that of Ascension, where we know thck'c is not one native sjrccies of the Order. 



