414 



Francis Beaufort, for communication to Baron Alexander von Hum- 

 boldt, which has been laid before the Linnean Society [see Phytol. 

 iv. 28]. In illustration of his paper Mr. Mossraan exhibited a fine 

 specimen of Sargassum bacciferum, and presented the same to the 

 Society's herbarium. 



Dr. Greville remarked that Mr. Mossman had given a very full and 

 complete account of all that was known relative to this sea-weed. Dr. 

 G. believed that the gulf-weed was, no doubt, at some period of its 

 existence attached to rocks, as indicated by its disk-like root. These 

 so-called roots of sea-weeds, however, he thought, only acted as hold- 

 fasts {crampons) , and were not the organs of absorption as in ordinary 

 plants. Sea-weeds absorbed throughout their whole substance, and 

 the use of their roots was to allow them to grow in favourable circum- 

 stances for taking up nourishment. He considered that it was highly 

 probable that the gulf-weed increased by lateral shoots when floating 

 in the sea. This he was the more disposed to believe, from what he 

 had seen in the case of Fucus Mackaii. He had observed this sea- 

 weed on the coast of Skye, and on various parts of the west coast of 

 Scotland, northwards as far as Cape Wrath, filling up bays at certain 

 seasons, and growing with its branches upright, in loose mud, without 

 any attachment. Among thousands of such plants, forming a close 

 meadow of sea-weeds, he was not able to find a trace of roots. The 

 plants seemed to thrive and vegetate luxuriantly. 



2. ' On the Correspondence between the Angles formed by the Veins 

 of the Leaves, and those formed by the Branches of the Stem ; by Mr. 

 William Mitchell, Edzell (communicated by the Rev. Dr. M'Cosh). 

 Having been informed that the Rev. Dr. M'Cosh had thrown out the 

 idea that a plant, considered morphologically, may be regarded as a 

 unity ; and, in proof of this view, had produced many examples 

 among forest trees, pointing to the similarity of the ramification of 

 the branches and the venation of the leaves, the general correspon- 

 dence of the angles in both, and the agreement of the form of the leaf, 

 or leafage from one point, with that of the whole tree ; I felt inclined 

 to test the truth of the theory, so far as I was able, by its application 

 to herbaceous plants. For this purpose 1 examined a great number 

 of these plants, and found the results, generally, the same as those 

 given in the following list, which contains a few of the most carefully- 

 measured of our common wild flowers : — 



Tansy {Tanacetum viilyare). The angle which the branches of this 

 plant makes with the stem is 45 deg., and it is equal to that which 

 the side veins of the leaf make with the central vein. In the other 



