240 Observations on Humboldt's Works 



.causes, or through hybrid generation, can be converted into 

 another ? S^c. Sfc. 



This distinction appears to me the more natural and proper, 

 because the geography of plants is founded wholly upon obser- 

 vation ; whereas a part of the history of plants rests upon hypo- 

 thesis. We may then certainly regard, as separate branches of 

 science, the geography, the geognosy, and the oeconomical his- 

 tory, of plants. 



1, Number of known Plants, and their distribution 



IN THE DIFFERENT PARTS OF THE WoRLD. (p. vii. xi.) 



The author mentions 38,000 as the full number of* phanero- 

 gamous plants known in catalogues and herbaria. 



It does not appear to me, by any means proper to refer to 

 herbaria in calculations of this sort ; since no person can have 

 the opportunity of seeing every collection of plants, and con- 

 sequently such calculation cannot be accurate. This actually 

 appears to be the case with the reckoning of the author ; of the 

 supposed 13,000 plants of South America, he takes 4,500, or if 

 we include those discovered by himself, 7,500 as the number 

 known in catalogues (Schriften), the remaining 8,500 or 5,500, 

 are then to be met with, only in herbaria. To the torrid zone of 

 Asia, he assigns, on the contrary, only 4,500; but since quite as 

 many belonging to this district are already to be found in cata- 

 logues, the author scarcely appears to have brought those which 

 are in herbaria, into calculation. But he has enjoyed oppor- 

 tunities of seeing plants collected in this portion of the globe, as 

 well as in America, and ought therefore, to have allotted a much 

 larger number to the torrid zone of Asia. If we were to regard 

 only those plants, which have been made known through cata- 

 logues, the highest number we could admit, would be 30,000, 

 for Persoon's Synopsis contains only 21,000 ; but take into con- 

 sideration all the herbaria, and the number 38,000 is certainly 

 too small. 



But in my opinion, much more weighty objections may yet be 



* Plants possessing visible stamens and pistils, or visible organs of 

 fructification.— T. 



