Botanical Society of Edinburgh. 425 



dulosus) having " caule sumrao pedunculisque glanduloso-hispidis," 

 which we believe to be the plant before us and that found by Mr. 

 Hardy. Of the above characters the gland-tipped hairs are alone of 

 any value. To have down at the base of the involucre is probably a 

 frequent condition of S. oleraceus, not oi S. asjier. The form of the 

 leaves is too inconstant to be of any value.] 



4. Dr. Balfour described a specimen of Stiftia chrysantJia, one of 

 the arborescent Compositse of South America, which had recently 

 flowered in the Edinburgh Botanical Garden. Also a specimen of 

 Quassia amara, which had shown flowering racemes. The leaves 

 of the latter presented remarkable transitions from a siinple to a 

 pinnate leaf, with a winged petiole. Notices of these will appear in 

 the ' Edinburgh New Philosophical Journal.' 



April 12. — Professor Balfour, President, in the Chair. 



The following communications were read : — 



1. "Algae Orientales " (part 8), by Dr. Greville. In this com- 

 munication Dr. Greville described Sargassum gracile, S. leptophyllum, 

 and S. flexile. This paper will appear in the ' Annals of Natural 

 History ' and in the Society's Transactions. 



2. " On the Irritability of the Style of various specfes of Gold- 

 fussia," by J. S. Sanderson, Esq. In this paper Mr. Sanderson 

 entered into a detailed statement of the structure of the style of 

 Goldfussia, and endeavoured to show that the explanation given by 

 Morren of the cause of the movements is not satisfactory. 



The style of Goldfussia curves outwards, the stigmatic papillae 

 occupying the convexity of the curve. The irritability resides in 

 the papillae. The change produced by irritation consists — 1st, in 

 the disappearance of the curve, the style being brought into the 

 straight position ; 2nd, in its being curved in the opposite direction 

 to a greater or less extent. In the moving part of the organ, or 

 that corresponding to the stigmatic surface, the arrangement of the 

 parts is the same as in Mimulus. An elastic epidermis covers the 

 surface opposite to that occupied by the stigmatic papillae. The 

 vessels and cylindrenchymatous tissue are interposed, the former 

 being in apposition to the epidermis, the latter occupying the re- 

 mainder of the space. Spiral vessels contribute to the elasticity of 

 the stigma. 



The cylindrenchyma appears to be the tissue in which the changes 

 are produced, giving rise to the irritability. The true stigma of 

 Goldfussia, like that of Mimulus, consists of a surface presenting^ 

 conical papillae, in connexion with which are the cylindriform cells, 

 which are continuous with those forming the general conducting 

 tissue of the style. In Mimulus and in Goldfussia anisophylla each 

 cylindriform cell terminates in a papilla. Hence Morren deduces an 

 explanation which he considers tenable, and which he gives as the 

 conclusion to be drawn from his researches. He supposes that the 

 motion of the style depends on a sudden transference of the granules 

 which are lodged in the papillae to the opposite extremities of the 

 cylindrical cells. This phaenomenon he believes to be dependent on 



