288 



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 Amygdalece, the leaves of several of which 

 are eminently poisonous, in consequence of containing, or producing, 

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

 oil abounds most in the leaves of the cherry-laurel fCerasus lauro- 

 cerasus), when they are young and undeveloped, and that it goes 

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

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

 season, when the old leaves, 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. 



" The consideration of this fact led to some statements upon the 

 mode and form in which some essential oils, and other active prin- 

 ciples, exist in the leaves of plants; and the conclusion was drawn, 

 that in all probability many active principles, which are separated 

 from plants by simple processes, do not exist ready formed in the 

 leaves ; but, as in the familiar case of the mustard-seed and bitter 

 almond, are only developed when the structure of the leaves is 

 broken up, and principles of a different kind, secreted in distinct 

 cells, are brought in contact with one another, or with water. 



" The remaining departments of the investigation were postpon- 

 ed ; but further observations were promised, upon the influence of 

 the progress of vegetation on the Solanaceous and Umbelliferous 

 plants; and likewise on the effects of soil and climate." 



2. A Specimen of Clavagella Balanorum (Scacchi), presented 

 by Sir Thomas Brisbane, Bart., President of the Society, 

 was laid on the table, with the following Remarks by Dr 

 Traill. 



" This is a rare and interesting species of Clavagella, now inha- 

 biting the shores of Naples, presented by Sir Thomas Brisbane. 



" When that part of Lamarck's work on Invertebrata, which con- 

 tained the class ConchifercB, appeared in 1818, among the order 

 TuhicolcB, he introduced the genus Clavagella, of which he describes 



