48 CHAPTER OF VARIETIES. 



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 iu animals under similar circum- 

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

 Centaurea atro-purpurea, and of the Malvaceae. DAVID DON. 



CA USE 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. 



Tootiny, November ~22d, 1832. 



