139 



action of poisons on plants by M. Miquel* : for the most part 

 sections of plants were employed, and the effect of caustic am- 

 monia, acetate of lead, tincture of galls, camphor, cherry-laurel 

 water, extracts of opium and Hyoscyamus on them observed. 

 The effect of ammonia and camphor in a gaseous form also 

 was noticed, and M. Miquel obtained in general from all his 

 numerous experiments results quite similar to those already 

 established by his predecessors. I will however here add one 

 observation, namely, that the velocity with which the various 

 poisons act upon the severed parts of the plant depends en- 

 tirely on their evaporation, for only in consequence of this does 

 the plant absorb the water with the poison, &c. ; it is conse- 

 quently necessary that in all such observations, if in future it is 

 desired to obtain coincident results, the state of moisture 

 and the warmth of the air be observed. 



Geography of Plants. 



The interesting communications which Alexander von Hum- 

 boldtf has published on his ascent of the Chimborazo, con- 

 tain some important facts relative to the geography of plants 

 which at the same time must be regarded as correcting the 

 statements of Major Hall, published in this journal (Wieg- 

 mann's Archiv) in 1835. Above the height of 9720 feet A. v. 

 Humboldt found the Chimborazo surrounded with large plains 

 which lie step-like one above the other; the first step is 10200 

 feet high, the second 1 1 700, and they are so horizontal that it 

 seems as if one were looking upon the bottom of an ocean. The 

 very extensive downs (las Pajonales) are, on the Chimborazo, 

 as well as everywhere around the high peaks of the Andes, so 

 monotonous that the family of the grasses (species ofPaspalum, 

 Andropogon, Bromus, Deyeuxia, Stipa,) are rarely supplanted by 

 dicotyledonous plants, in which respect the vegetation exhibits 

 great similarity to the Steppes of Northern Asia. Only Cal- 

 ceolaria, Composites, and Gentiance (among which G. cernua, 

 with purple-red flowers) present themselves in those elevated 

 plains among the gregarious grasses, which, for the greater 

 part, belong to North European genera. The mean tempe- 

 rature of these heights also nearly agrees with that of North- 



* Proeven overde Werkingvan Vergiften ofPlanten. Tijdschrift v. Nat. 

 Geschied. en Physiol. 1837, iv. p. 154208. 



t Ueber zwei Versuche den Chimborazo zu besteigen. Schumacher's 

 Jalirbuch fur 1837, p. 176206. 



