178 CHARLES DARWIN 



The appearance was very similar to that which might be 

 expected from a large fish moving rapidly through a lumi- 

 nous fluid. To this cause the sailors attributed it; at the 

 time, however, I entertained some doubts, on account of the 

 frequency and rapidity of the flashes. I have already 

 remarked that the phenomenon is very much more common 

 in warm than in cold countries; and I have sometimes im- 

 agined that a disturbed electrical condition of the atmos- 

 phere was most favourable to its production. Certainly I 

 think the sea is most luminous after a few days of more 

 calm weather than ordinary, during which time it has 

 swarmed with various animals. Observing that the water 

 charged with gelatinous particles is in an impure state, and 

 that the luminous appearance in all common cases is pro- 

 duced by the agitation of the fluid in contact with the atmos- 

 phere, I am inclined to consider that the phosphorescence is 

 the result of the decomposition of the organic particles, by 

 which process (one is tempted almost to call it a kind of 

 respiration) the ocean becomes purified. 



December 2$rd. We arrived at Port Desire, situated in 

 lat. 47, on the coast of Patagonia. The creek runs for 

 about twenty miles inland, with an irregular width. The 

 Beagle anchored a few miles within the entrance, in front of 

 the ruins of an old Spanish settlement. 



The same evening I went on shore. The first landing in 

 any new country is very interesting, and especially when, as in 

 this case, the whole aspect bears the stamp of a marked and 

 individual character. At the height of between two and 

 three hundred feet above some masses of porphyry a wide 

 plain extends, which is truly characteristic of Patagonia. 

 The surface is quite level, and is composed of well-rounded 

 shingle mixed with a whitish earth. Here and there scat- 

 tered tufts of brown wiry grass are supported, and still more 

 rarely, some low thorny bushes. The weather is dry and 

 pleasant, and the fine blue sky is but seldom obscured. When 

 standing in the middle of one of these desert plains and 

 looking towards the interior, the view is generally bounded 

 by the escarpment of another plain, rather higher, but equally 

 level and desolate; and in every other direction the horizon 



