332 Dr. G. Dickie on the Marine Alga 



Some diflFerence of opinion has arisen respecting the nature of 

 the frond in this plant ; the peziziform expansion being consi- 

 dered by some as the true frond, and the elongated part as a true 

 receptacle. In a paper on the Botany of the Antarctic Expedi- 

 tion, published in the ' London Journal of Botany^ for June 1843, 

 Dr. J. D. Hooker states his belief, that the frond of Himanthalia 

 is an abortive bladder analogous to the trumpet of Ecklonia buc- 

 cinalis, and finds no reason to suppose that the thongs are recep- 

 tacles. He believes that Himanthalia, Ecklonia and Durvilleca 

 will form a distinct group. 



The young fronds are well represented by Dr. Greville in his 

 * Algse.^ A section shows first a cortical part composed of dense 

 tissue, beneath which there is a subcortical less dense than the 

 former and more transparent ; in the centre the tissue is com- 

 posed of jointed and branched filaments, whose general direction 

 is from base to apex of the small dilated frond : this tissue is 

 highly elastic. The young frond is at first turgid with a fluid 

 partly mucus and partly water. At an early period there is no 

 distinct stem, the vesicle being attached by a flat disc. At a more 

 advanced stage, however, the stem becomes evident, and its ge- 

 neral structure is the same as that of the vesicle itself, three di- 

 stinct tissues being present ; sometimes two vesicles originate fi-om 

 the same flat disc or root, and then one is usually larger than the 

 other. 



In a more advanced stage the stem becomes very distinct, ha- 

 ving increased in proportion more rapidly than the inflated part. 

 The vesicle afterwards becomes depressed in the centre, at which 

 time a firm band of fibrous tissue connects the stem with the disc 

 of the inflated part, and the two come in close contact, thus pro- 

 ducing a depression in the centre of the vesicle, all which is pro- 

 duced by the contraction of the central fibrous band alluded to. 



The thongs, or receptacles, first appear as small papillse in the 

 centre of the depressed portion, and are intimately connected 

 with the above-mentioned fibrous band, their central tissue being 

 continuous with it, and their outer with the cortical part of the 

 vesicle. 



Mrs. Griffiths and Dr. Greville believe the plant to be annual. 

 Capt. Carmichael considered the cup alone to be perennial and 

 the thongs annual ; he also supposed that every part of the cup 

 is capable of producing them, as he found them eccentric in old 

 plants. I have never seen them eccentric excepting where the 

 frond had become distorted from injury produced by the attacks 

 of small mollusca and Crustacea. The thongs are continuous 

 with the fibrous band already mentioned, and cannot therefore, 

 properly speaking, be eccentric. The peziziform part is produced 

 one season, and in the following forms receptacles, which, when 



