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stances of vegetation, more especially climate, weather, soil, and the 

 progress of vegetation. He then stated the sources of information 

 on these points, namely, the curative or therapeutic action «»f drugs 

 on man, — their effects on the healthy functions both of man and 

 animals, either as medicines or as poisons, — their sensible qualities, 

 — and their chemical analysis ; and he assigned reasons for discard- 

 ing the first of these from the inquiry, and for trusting, in a great 

 measure, to the criterions derived from sensible qualities, — from 

 the effects of poisons on the lower animals, — and from chemical 

 analysis. 



" The remaining part of the present paper was confined chiefly 

 to the influence of the Progress of Vegetation on the activity of 

 plants. Doubts were thrown by the results of his investigations 

 on most of the current doctrines on this head ; but the present state 

 of the inquiry did not lead to any general inferences being drawn 

 with confidence. 



" An extended statement was made upon the influence of the 

 progress of vegetation upon many of the active species of the natu- 

 ral family Ranunculacea:. It was stated, that, in the acrid species 

 of the genera Ranunculus, Anemone, and Clematis, the acridity, 

 which is the same throughout them all in quality, is possessed in 

 nearly equal activity by the leaves, from an early period in the 

 spring until they are about to decay ; but that it exists in the ger- 

 mens only while they are green, and disappears there entirely as 

 the seeds ripen. In the acrid species oi Aconitum, the acridity of 

 the leaves, tm the contrary, continues only until the seeds begin to 

 form, and then gradually, but quickly, disappears as they ripen, 

 while the seeds acquire precisely the same peculiar kind of awidity. 

 The narcotic properties of the leaves, however, do not undergo the 

 same singular change, bnt contiime undiminished after the seeds are 

 mostly ripe, and probably, indeed, as long as the leaves themselves 

 retain their freshness. The acridity of the genus Helleborus is pro- 

 bably governed by circumstances different from any of those already 

 mentioned ; but the experiments already made are insuflScient to 



point out the true rule In the course of these observations many 



remarks were also made on the nature of the acridity possessed by 

 the different species, upon which incorrect ideas at present very 

 generally prevail ; several material corrections were also suggested 

 as to the general opinions respecting the influence of heat, desicca- 

 tion, and time, upon their acridity ; and a short allusion was made 

 to the properties of a remarkably crystalline principle which the 



