406 Proceedings of the. Bopal Society. 



the effects of poisons on tlie lower animals, — and from cbemical 

 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 investigatious 

 on most of the current doctrines on this head ; but the pi'eseiit 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 Ranuticnlacece. It was stated, that, in the acrid species 

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

 which is the same tl'roughout 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 Aconilum, the acridity of 

 the leaves, im 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 acridity. 

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

 same singular change, but continue undiminished after the seeds are 

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

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

 bably governed by circumstances different from any of those already 

 mentioned ; but the experiments already made are insufficient 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 

 author discovered in one of the species of Ranunculus, and which 

 appeared to him to be the ingredient upon which the activity of 

 that genus depends. 



" The author next entered into some details regarding the influ- 

 ence of the progress of vegetation on narcotic plants, and commenced 

 with the natural family AmygdalecB, the leaves of several of which 

 are eminently poisono\is, in consequence of containing, or producing, 

 when bruised, a hydrocyanated essential oil. He shewed that this 

 oil abounds most in the leaves of the clierry-laurel ( Cerasus lauro- 

 cerasusj, when they are young and undeveloped, and that it goes 

 on dimniishing gradually in proportion to their weight, as they in- 

 crease in age and vigour, until the commencement of their second 

 season, when the old lea/es, though plump and luxuriant, do not 

 contain above an eighth or tenth of what they contained in the in- 

 fant state, or of what is contained in the young undeveloped leaves 

 of the same period. This is a complete reversal of the generally- 

 admitted law in respect of the formation of volatile oils in leaves. 



