Falklands, ete.) CRYPTOGAMIA ANTARCTICA. 153 
Fructification forming a large oblong or linear sorus between the base and middle of the frond, of a rich 
red-brown colour when held between the eye and light, imbedded in the thickened substance of the frond, which 
decays with it. On a transverse section the soriferous lamina is seen to be hollow in the centre; or rather the 
sorus is formed of two parallel plates, each covered externally with densely aggregated spores, which occupy what 
are the superficial cells of other parts of the frond. Below the superficial series of cells, and especially in fertile 
specimens beneath the spores, are several, 4-6 or many more, air-cavities, reposing on, and separated from each other 
by a loose cellular tissue, which is hexagonal, transparent, the cells becoming transversely elongated and finally 
towards the centre of the frond breaking up into a layer of matted filaments, which surrounds the cavity, a 
structure resembling very closely that of Fucus confluens as given by Turner. When dry, the surface of the plant is 
covered with white efflorescence, similar to that of Laminaria saccharina, it has been analysed by my friend 
Mr. Stenhouse of Glasgow, who finds it to contain excellent Manna, and who further informs me that this and 
the other larger Antarctic 4/ye are peculiarly rich in Iodine. 
The Lessonia quercifolia of Bory, is described and figured as having the frond covered with cavities containing 
spores, whence it would appear to belong to Fucoidee, and to be more allied to D’ Urvillea than to this genus. 
Lessonia ciliata of Postel and Rupprecht, is certainly only the young state of Macrocystis pyrifera. 
Prare CLXVII.—CLXVIII.—C. transverse section of frond in fructification :—highly magnified. 
3. Lessonia ovata, Hook. fil. et Harv.; stipite brevi vage dichotome ramoso, ramis brevibus divaricatis, 
frondis laciniis breviter petiolatis, petiolo in laminam ovatam lineari-ovatamve olivaceo-fuscescentem submem- 
branaceam dilatato. (Tas. CLXVIIL.—CLXVIIL. B; et Tas. CLXXI. C.) 
Has. Hermite Island, Cape Horn, and the Falkland Islands; very abundant. 
Radix e fibris perplurimis crassis intricatis massam 1-2 ped. latam efficientibus. Stipites e radice plurimi (ut in 
Macrocysti) 4—6 unc. longi, torti v. flexuosi, crassitie pollicis humane, dichotome fissi, demum. solitarii, incrassati, 
subarborescentes. Lamine pedales, colore et substantia Z. fuscescentis, juniores basi obscure sinuato-dentatee ; 
adulte integerrimee. 
Certainly very near Z. fuscescens; but as far as could be judged on examining the plant, both on the shores it 
inhabits and in the herbarium, it has good claims to be considered a distinct species, especially in the many short 
stipites, short branches and broad leaves. Never having seen the fruit, however, it may prove the young of 
L. fuscescens, for we can well suppose only one out of the many stems of that plant to attain any great dimensions, 
and the lamina of the young state to be broader than that of the adult. 
The ramification of all the species of Lessonia is dichotomous; each plant in a young state consists of a few 
rooting and clasping fibres, giving off a single stem (or petiole) and frond. This frond splits at the base, and as 
the growth proceeds, the fissure extends vertically upwards, till the original frond is bisected ; each of the two 
parts is now a complete frond, altogether similar to the primary one, and provided with a petiole of its own: these 
again divide, and the process is repeated. Hence the rapid growth of this genus, and hence the origin of the 
flattened form of ramuli and elliptic core which is placed in the long axis of these ramuli and across the axis of the 
terete stem. It was not observed whether any relation existed between the number of branches on the whole frond: 
and of concentric rings in the trunk. The latter are probably the indices of the number of times that a subdivision 
of the lamine has occurred, supposing that all split at about the same epoch, rather than a register of the years 
the vegetable has existed; as the following account of the anatomy of this species will show. 
A branched portion of the plant, terminated by four laminz, necessarily presents súbdivisions of three periods 
of growth: lst, the petioles of the four lamin; 2nd, the two ramuli from which the four are given off; and 3rd, 
the one branch which gives off the two latter: these were successively examined. 
1. The base of the lamina or petiole is exceedingly compressed, and composed of a mass of cellular tissue of 
PR 
a TSR —Á———— " 
