404 FLOEA ANTAECTICA. [Fuegia, the 



elongation of the upper part of a plant which never branches, and whose growth is independent of all below it, even 

 of the root. Specimens measuring between 100 and 200 feet are common in the open ocean, aud these are always 

 broken off at the lower end, either from the division of the frond by sea-animals, through whose agency the plant 

 increases and the floating island it forms dilates, or from the impossibility of securing the whole mass from the 

 motion of the vessel or the swell of the sea, in latitudes where no boat can be lowered. Again, D'Urville, upon 

 whose observations in natural history the utmost reliance may be placed, states it to grow in eight, ten and even 

 fifteen brasses of water, from which depth it ascends obliquely and floats along the surface nearly as far : this gives 

 a length of 200 feet. In the Falkland Islands, Cape Horn and Kerguelen's Land, where all the harbours are 

 so belted with its masses that a boat can hardly be forced through, it generally rises from eight to twelve fathom 

 water, and the fronds extend upwards of one hundred feet upon the surface. We seldom, however, had opportunities 

 of measuring the largest specimens, though washed up entire on the shore ; for on the outer coasts of the Falkland 

 Islands, where the beach is lined for miles with entangled cables of Macrocystis, much thicker than the human body, 

 and twined of innumerable strands of stems coiled together by the rolling action of the surf, no one succeeded in 

 unravelling from the mass any one piece upwards of seventy or eighty feet long ; as well might we attempt to 

 ascertain the length of hemp fibre by unlaying a cable. In Kerguelen's Land, the length of some pieces, which grew 

 in the middle of Christmas Harbour, was estimated at more than three hundred feet ; but by far the largest seen 

 during the Antarctic Expedition, were amongst the first of any extraordinary length which the ships encountered, 

 and they were not particularly noticed, from the belief that the report of upwards of 1000 feet length was true; 

 or, at any rate, that better opportunities of testing its truth would arise in the course of a three years' voyage, than 

 the first week of our explorations could afford. These occurred in a strait between two of the Crozet Islands, where, 

 very far from either shore, in what is believed to be forty fathoms water, somewhat isolated stems of Macrocystis 

 rose at an angle of 45° from the bottom, and streamed along the surface for a distance certainly equal to several 

 times the length of the ' Erebus '; — data, which if correct, (and we believe them so) give the total length of the 

 stems as about 700 feet. 



That isolated patches of weed should rise through such a volume of water is not incompatible with the state- 

 ments we have elsewhere made, that eight or ten fathoms is the utmost depth at which, judging by our experience, 

 submerged sea-weed vegetates in the Southern temperate and Antarctic Ocean. These exceptional cases are probably 

 due to the parent plant having attained such a size in its birth-place near shore, as to weigh its stony moorings 

 and deposit itself in deeper water, where an increase of the roots woidd unite the original base to other rocks, and 

 thus gain a footing that defies the power of the elements. 



We have stated that the elongation of the Macrocystis may be indefinite ; but this is only true partially and 

 in the case of detached patches : for the stem of the attached plant does not gain bulk or tenacity, after a 

 certain period ; whilst the growing dimensions of the floating portion are increasing the difference between the 

 specific gravity of the vegetable and the element it inhabits, and consequently augmenting the strain upon the 

 slender stem by which it is attached. At some period or other, the resistance is overcome and the floating part 

 detached from the submerged : though at what epoch this may take place, or whether it be coincident with other 

 phases in the life of the plant, is beyond our conjecture. 



The fact that fructification is produced only on the submerged young bladderless and small frond, within a few 

 inches of the very root, is highly remarkable. What then is the function of the floating mass of the plant ? to 

 one of whose thousand leaves, each four to six feet long, the fructifying part bears an inconceivably small pro- 

 portion. Were this a phaenogamic plant, we should recognize, in such foliaceous expansions, organs which fulfil a 

 respiratory and digestive office and are subservient and necessary to the development of the more important parts 

 of the vegetable ; but in this case such a mutual dependency is not so easily traced. As in Lessonia the multi- 

 plication of the leaves is intimately connected with the development in diameter of the stem, so in Macrocystis the 

 development of fructifying fronds may take place only at the root of the barren ones, on whose previous existence they 

 may be dependent for their origin. These are, however, questions which propose themselves to us in the closet only, 



