48 



CHAPTER OF V A KILTIES. 



On the temperature of shallows at sea. — The waters which 

 cover shoals owe the diminution of their temperature, in a great measure, 

 to their mixture with the lower strata of waters which rise towards 

 the surface on the edge of the banks. The proximity of a sand- 

 bank at sea is indicated by the rapid descent of the surface tem- 

 perature of the water. — Captain Williams. 



Spiral vessels of plants animated. — On detaching the spiral 

 vessels from vigorous young shoots of herbaceous plants, they frequently 

 become violently agitated : the motion continues for some seconds, and 

 may be similar to that of the heart in animals under similar circum- 

 stances. These vessels abound in the stems of the Urtica nivea, of 

 Centaurea atro-purpurea, and of the Malvacece. — David Don. 



Cause of volcanoes. — It is not long since it was thought that the 

 decomposition, and consequent ignition of pyrites, was sufficient to 

 account for volcanoes, &c, though they are rarely if ever found in lava 

 or other volcanic productions ; and they are still more rarely found at 

 all in masses of any extent. Besides, so long as they remain enveloped 

 in rocks, they are unalterable; and two or three species, even under 

 the most favourable circumstances, are decomposable with great dif- 

 ficulty ; and only one species — radiated pyrites, is capable of being 

 rapidly decomposed, but not unless it be broken or crumbled into 

 small portions, and not too much or too little moistened. — M. Cor- 

 dier. 



Attack upon a hare by a magpie. — To record the petty conflicts 

 of the inferior animals, may seem trifling to thegeneral observer ; but to 

 the naturalist, who writes the history of a species, no anecdote, how- 

 ever trivial, that serves to illustrate peculiar traits of character, can 

 appear .either uninteresting or superfluous. I was informed the other 

 day, by a friend, (a medical man, with whom I am on terms, and on 

 whose veracity I can rely), that he had just witnessed a curious con- 

 test between a magpie and a fine full-grown hare; the bird making 

 frequent and furious pounces at the hare, and pursuing it for a consi- 

 derable distance, when the animal escaped by making for a thick hedge, 

 at the other side of which it ran off to some distance from the place 

 where it had entered, and without being observed by the bird. I had 

 always considered the magpie to be a remarkably bold bird ; but 

 never conceived him capable of such an exploit as this. — Edward 

 Blyth. 



Tooting, November 22d, 1832. 



