Page:Aspects of nature in different lands and different climates; with scientific elucidations (IA b29329668 0002).pdf/134

 *[Footnote: *tion of fluids, is dependent on the pressure of the atmosphere. Therefore it is that alpine plants are more aromatic, and are hairy and covered with numerous pores. (See my work über die gereizte Muskel-und Nervenfaser, Bd. ii. S. 142-145.) For according to Zoonomic experience, organs become more abundant and more perfect in proportion to the facility with which the conditions necessary for the exercise of their functions are fulfilled,—as I have elsewhere shown. In alpine plants the disturbence of their skin-respiration occasioned by increased atmospheric pressure makes it very difficult for such plants to flourish in the low grounds.

The question whether the mean pressure of the aerial ocean which surrounds our globe has always been the same is quite undecided: we do not even know accurately whether the mean height of the barometer has continued the same at the same place for a century past. According to Poleni's and Toaldo's observations, the pressure would have seemed to vary. The correctness of these observations has long been doubted, but the recent researches of Carlini render it almost probable that the mean height of the barometer is diminishing in Milan. Perhaps the phenomenon is a very local one, and dependent on variations in descending atmospheric currents.]*