jg« ON TORPIDITY IN ANIMALS. 



birds of pas- which are seen in summer only ; but though the opinion has 

 sa S 0, had its advocates as long ago as Pliny, it has never been 



proved, and perhaps it never will. For since the cricket 

 avoids the cold when it can, and the woodcock, as well as 

 the snipe, retires from the north at the end of autumn with 

 the same intention ; it is highly probable, that the swallow, 

 with many more periodical birds, quits this country, and 

 flies to warmer regions on the approach of winter; while the 

 bat, the dormouse, and hedgehog, are obliged to abide the 

 rigours of the season, benumbed by the frost and debilitated 

 by hunger. But it is time to return from this digression, 

 and to come to the second objection, the proof of which is 

 contained in the following experiment. 

 The second I took several specimens of the garden snail, helix Jtortensis, 



°m^ified bv anc * s ^ ut tnena U P m a perforated wafer box ; which secluded 

 two kinds of them from food and water, but not from air. A number of 

 snails, t | ie fefe ZQnar ' ia was treated in the same manner; and a few 



of this species were put into a bottle, which was corked, to 

 cut off all communication with the atmosphere, as well as 

 food and water. Those snails did not live long which were 

 deprived of air; but the specimens of both species did not 

 die which were confined in the perforated boxes. On the 

 contrary they retired into their shell, closing the apertures 

 of them with thin membranes; here they remained dead to 

 all appearance, as long as I kept them dry. But this death 

 was nothing more than apparent; for I restored my prisoners 

 to life in succession, by dropping them into a glass con- 

 taining water of the temperature of 70° or 72°: after leav- 

 ing them four or five hours in this fituation, I constantly 

 found them alive, and sticking to a plate which covered the 

 vessel. A large garden snail supported this severe confine- 

 ment nearly three years, being apparently dead all the time; 

 after which it revived upon being put into water, like the 

 .rest of its fellow captives. 



This wonderful faculty however is not possessed by snails 

 of every description; this I discovered, by treating an aqua- 

 tic species, the helix putris, in the manner described above. 

 The preceding experiment was made in consequence of a 

 short memoir which I met with some years ago, in a volume 

 of the Philosophical Transactions of an older date. The 



writer 



