338 OBSERVATIONS ON THE CURRENTS. 



Europe, and appears among the other sea-weeds in the various 'works oa 

 algology, but it is accepted as a shipwrecked stranger, not as a native of 

 our shores. 



(295.) The Gulf of Mexico abounds with the native growths of the Sar- 

 gasso weed. It is found attached to the rocks, at the bottom, in most parts 

 of it. The soundings on the Campeche Bank, Chiriqui, the Andros Islands, 

 on the Bahama Banks, New Providence, &c., all furnish the supply of 

 growing plants. The spores (or seeds) of these become attached to these 

 rocks in the manner usual with all alga, and the young plant grows, not 

 from a root, because the attachment to the rock is not of that nature, till 

 it attains some size, when offering greater resistance to the progress of the 

 continual current than the stalk is able to bear, it becomes detached, rises 

 to the surface, and then is borne onward by the stream till it emerges 

 through the Gulf of Florida by the Gulf Stream. As will be shown here- 

 after, this stream has a tendency to throw all floating bodies off to the 

 right-hand of its course; it follows, that this weed is gradually cast off into 

 this central area, aided probably by the Westerly prevalence of the winds 

 which at times occur in this part. 



One opinion may be safely controverted, that which assigns the depths 

 of the Atlantic over which it is found as its native place. The great depth 

 and consequent cold disproving the possibility of a plant living in such 

 extremes of temperature. 



In the Paper mentioned in the note on page 335, Dr. Kriimrael calcu- 

 lates that after leaving Florida Strait or its vicinity, it would take about 

 six months for this weed to reach a position West of the Azores. It then 

 moves away very slowly, and gradually decays and sinks. 



(296.) H.M.S. Challenger, in crossing the Sargasso Sea (June 14th to 

 July 1st, 1873), found the Current variable, both in strength and direction; 

 in 63= W. 19 miles N.B. ; in 59° W. 12 m. N.E. ; in 53° W. 6 m. S.S.E. ; 

 in 50i° W. 17 m. E. by N. ; in 49° W. 18 m. N.N.E. ; in 45° W. 6 m. 

 West; in 42° W. 22 m. N.W. ; in 38° W. 27 m. North ; in 36° W. 4 m. 

 North; in 35° W. 16 m. E.S.E., and in 32° W. 8 m. S.W. The depth 

 westward of 38° W. was between 2,000 and 3,000 fathoms, with a bottom 

 of oaze, and with no signs of weed, disproving entirely the idea of some 

 naturahsts that the weed grows in this locality. Eastward of 38° W., the 

 depth varied from 1,675 to 1,000 fathoms. The temperatures of the sea 

 surface were greater in the Western part of the district, 73^°, than in the 

 Eastern, where it was generally found to be about 71°; at 100 fathoms the 

 temperature was about 66° ; at 500 fathoms about 48^° ; and at 1,000 

 fathoms about 37|° Fahrenheit. 



" The floating islands of the gulf- weed, with which we had become very 

 familiar, as we had now nearly made the circuit of the 'Sargasso Sea,' are 

 usually from a couple of feet to two or three yards in diameter, sometimes 

 much larger ; we have seen, on one or two occasions, fields several acres 

 in extent, and such expanses are probably more frequent nearer the centre 

 of its area of distribution. The general effect of a number of such fields 

 and patches of weed, in abrupt and yet harmonious contrast with the lanes 

 of intense indigo which separate them, is very pleasing. These floating 

 islands have inhabitants peculiar to them, and I know of no more perfect 



