250 Ohservatious on Humboldf^s Worhs 



plains towards the pole. If this be true (and it seems not to admit 

 of any doubt,) the Graminecey Labiatce, Ericince, and Rhodo- 

 dendrttf should afford a smaller quotient, when the plants of the 

 higher regions are excluded, than when they are taken into 

 the calculation ; the Leguminosce and Comjpositce, on the con- 

 trary, a greater. The Juncece, whose number according to this 

 reasoning, should be smaller in this place, are given as -j^^, 

 although before as -^^ ; the Malvacece, the number of which 

 should be greater, are given as 3^^, but before as ^. 



Whether the author, when treating of the second zone, has 

 excluded the plants of the higher districts, I cannot determine, 

 since, as has been already mentioned, I do not know the au- 

 thorities which he employs. From the proportions, mentioned 

 in the notes to the table, this does not appear to be the case, 

 for the numbers correspond exactly with those given before. 



Page 33, the author treats of the distribution of the 1,000 

 fernsj which are at present known. But here also those which 

 grow in the higher regions are not excluded. 



When an extensive family of plants contains many smaller 

 families, or groups, which present a different, or entirely op- 

 posite geographical distribution; it seems proper, not merely 

 to consider the distribution of the entire family, but likewise 

 that of each group in particular. This the author has observed 

 in respect to the Glumacece, three subdivisions of which, Gra- 

 tninece, Cyperoidece, and Juncece, are treated of separately : but 

 not so in the Compositce. Besides, is it not surprising that 

 Jussieu's Cichoracece are quite excluded from the equatorial 

 zone *. 



This group, however, certainly diminishes from the temperate 

 zone towards the equator. The whole family of the Compositce 

 should, according to M. Humboldt, diminish from the equator 

 towards the poles. Willdenow affirms the contrary f. The 

 numbers given by M. Humboldt for the equatorial and tem- 



* About 340 species are enumerated in Pbrsoon's Synopsis, at least 

 4 — 5 within the tropics. 



t Grundriss der Kraiiterkunde, p. 484, und Magazin [der Gesellschaft 

 naturf. Freunde zu Berlin, later. Jahrgang, 2tes. Stuck, p. 133. 



