28 



A letter, dated May 19, 1845, addressed by the President to Admiral 

 Sir Francis Beaufort, for communication to Baron Alexander 

 von Humboldt, on the Origin and Mode of Propagation of the 

 Gulf -weed. 



" My dear Captain Beaufort, — I am vexed to have kept Baron 

 Humboldt's letter so long, and now in returning it, that it should be 

 accompanied by so little satisfactory information on the only one of 

 its queries with which I could have been supposed to deal, namely, 

 that which relates to the origin and mode of propagation of the Gulf- 

 weed. 



" On this subject it appears that M. de Humboldt (in his Personal 

 Narrative) first supported the more ancient notion, that the plant, 

 originally fixed, was brought with the stream from the Gulf of 

 Florida, and deposited in what Major Rennell calls the recipient of 

 that stream. More recently, however, Baron Humboldt has adopted 

 the opinion,* also held by several travellers, that the Gulf-weed 

 originates and propagates itself where it is now found. To the 

 adoption of this view it appears that he has been led chiefly by the 

 observations of the late Dr. Meyen, who in the year 1830 passed 

 through a considerable portion of the great band of Gulf-weed, and 

 who ascertained, as he states, from the examination of several thou- 

 sand specimens, that it was uniformly destitute both of root and 

 fructification ; he concludes, therefore, that the plant propagates 

 itself solely by lateral branches : he at the same time denies that it 

 is brought from the Gulf of Florida, as, according to his own obser- 

 vation, it hardly exists in that part of the stream near the great band, 

 though found in extensive masses to the westward. I have here to 

 remark that, as far as relates to the absence of root and fructification, 

 Meyen has only confirmed by actual observation what had been 

 previously stated by several authors, particularly by Mr. Turner (in 

 his 'Historia Fucorum,' vol. i. p. 103, pubHshed in 1808), and 

 Agardh (in his ' Species Algarum,' p. 6, published in 1820). But 

 Meyen materially weakens his own argument in stating that he 

 considers the Gulf-weed {Sargassum hacciferum of Turner and 

 Agardh), and the Sargassum natans, or vulgare, specifically dis- 

 tinguished from it by these authors, as one and the same species ; 

 adding, that he has observed among the Gulf-weed all the varieties 



* Histoire de la Geographie du Nouveau Continent, vol. iii. p. 73, and Mcycn, 

 Reise, vol. i. p. 36 — 9. 



