304 Botanical Society of Edinburgh : — 



long remained unquestioned. Some years ago Dr. Weddell discovered 

 peculiar glands in Cinchonacese, and the results of his observations, 

 as well as of my own, on the similar glands of Galiacese were detailed 

 to the Society (Ann. Nat. Hist. ser. 2. xiv.). The homological 

 character of these glands was not then referred to ; for when viewed 

 in connexion with the glands of Sundew and some other plants, their 

 structure did not appear explicable on the supposition that they 

 were formed of epidermal cells. Since my former paper was pub- 

 lished, an extended series of observations on vegetable glands, and 

 especially on the stipules of plants belonging to the Apocynaceae, has 

 shown that the cinchonaceousf glands, and all other forms, are re- 

 concilable with the idea of epidermal origin. The cinchonaceous 

 gland consists of two kinds of cells, one of which represents ordinary 

 leaf-tissue, and the other may be regarded as the epidermal cells 

 transformed for secretion. The gland is, in fact, the homologue of 

 the leaf, — a leaf very much reduced in size, as stipular leaves usually 

 are, and with its epidermal cells changed into secreting ones ; and it 

 closely resembles in structure the stipules of Dipladenia, which no 

 one can regard as being other than reduced leaves. When we see a 

 gland thus formed by a cone of tissue elevated above the general 

 surface of the organ to which it is attached, with its whole epidermal 

 surface consisting of secreting tissue, we can readily understand how 

 an epidermal gland can also be formed in the tissue of the plant, by 

 simply introverting the epidermis. In this way the remarkable 

 ovarian glands of endogenous plants are explained, and probably also 

 the imbedded glands of the Orange, the latter bearing the same rela- 

 tion to the cinchonaceous gland as the conical receptacle of the 

 Strawberry does to the hollowed-out receptacle of the Fig. The ova- 

 rian glands of Endogens are especially deserving of attention on this 

 point, for we find them of very frequent occurrence ; and in cases 

 where three or more carpels are united into one fruit, these glands 

 always occupy a position corresponding with the points of union of 

 the carpels. Irrespective of histological characters, the glandular 

 tissue is seen in these cases to be necessarily formed by the contiguous 

 layers of epidermis where the two surfaces of the carpels are brought 

 into contact. 



5. " On the Development of the Yeast Plant," by Mr. John Lowe* 

 Mr. Lowe observed, that, under the microscope, brewers' yeas* 

 consists entirely of cells, spherical in form, transparent and nucleated, 

 varying from -y-gVpth to ^oo^li of an inch in diameter. The nuclei 

 are highly refractive, and vary from two to ten in number. These 

 nuclei were termed *globuline' by Turpin. 



The growth of yeast has been divided by Pereira into three stages. 

 1 st, that in which the cells are single ; 2nd, that in which they have 

 become elongated, and form a mycelium ; 3rd, that of aerial fructifi- 

 cation. The first stage, or that of yeast proper, is said by Mitscher- 

 lich to consist of two kinds, viz. Oherhefe (or surface-yeast) and 

 XJnterhefe (or sediment-yeast). These two varieties are propagated 

 ^* different ways, and each produces specific results upon the fer- 



