164 PORT DESIRE. [cmap. vii. 
over, without disturbing these patches. ‘Therefore we must sup- 
pose that some animals were congregated together at a greater 
depth than the bottom of the vessel. 
Near Fernando Noronha the sea gave out light in flashes. 
The appearance was very similar to that which might be expected 
from a large fish moving rapidly through a luminous fluid. 
To this cause the sailors attributed it; at the time, however, I 
entertained some doubts, on account of the frequency and rapid- 
ity of the flashes. I have already remarked that the phenome- 
non is very much more common in warm than in cold countries ; 
and I have sometimes imagined that a disturbed electrical con- 
dition of the atmosphere 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 produced by the 
agitation of the fluid in contact with the atmosphere, IT am in- 
clined 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 23rd.—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 scattered 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 
