775 



"Finally the author refers to the horizontal separations in the cap- 

 sules of Mosses, and observes that the separation of the calyptra af- 

 fords a plain example of the operation of his third principle ; but 

 with regard to the nature of the operculum, although he has an hypo- 

 thesis under consideration, his mind is not yet satisfied. He states 

 his object in the present paper to have been the investigation of the 

 immediate physical causes of certain known effects, but he has not 

 thought this the place even to touch upon their ultimate causes or the 

 ends to accomplish which they are apparently designed, and which 

 adapt them to the position and general structure of the particular 

 plant." — Proc. Linn. Soc. No. xxviii. p. 273. 



BOTANICAL SOCIETY OF EDINBURGH. 



Thursday, February Wth, 1847. — Dr. Greville, President, in the 

 chair. 



Letters were read from Professor De Candolle, Geneva, and Marius 

 Barneoud, Paris, announcing donations ; and from Capt. Portlock, 

 giving a short account of his horticultural proceedings at Corfu, and 

 suggesting the Convolvulus Batatas, or sweet potato, as a substitute 

 for the potato ; — the plant has been introduced into Corfu, and appa- 

 rently with success. Capt. Portlock describes it as an excellent ve- 

 getable, being dry and between the potato and parsnip in taste. He 

 noticed having picked Orchis hircina, 18 in. high, at Butrinto, oppo- 

 site Corfu. 



The following communications were read : — 



1. "On the Defoliation of Trees," by the Rev. Dr. Fleming, After 

 refeiTing to the extremely defective nomenclature connected with the 

 " defoliation of trees," employed in the writings of Lindley, Gray, 

 and others, Dr. F. called the attention of the Society to a classifica- 

 tion of the phenomena which he had published in the ' Edinburgh 

 Journal of Science,' by Brewster, for January, 1826, and where leaves 

 are arranged in reference to their duration into three groups — Folium 

 deciduum, Folium annuum. Folium perenne. In the first class the 

 leaves cease to exercise their functions when the buds have been per- 

 fected, and fall off in succession before winter; or, when the plant is 

 trained as a hedge, they frequently remain until the evolution of the 

 buds in the following spring. In the second class the leaves outlive 

 the winter, and do not die or fall of!', until a number of new leaves 

 have been evolved for the support of the plant in spring or summer. 



