I. ANIMALCULA OF INFUSIONS. 77 



Some birds are alfo fubjedl to torpidity. At 

 the end of fummer, hundreds colled, duller to- 

 gether, and plunge into water, where they re- 

 main the whole winter in heaps, and ihrunk 

 within themfelves. The learned reader already 

 anticipates that I fpeak of fwallows. The fad is 

 too well circumftantiated, too well authenticated, 

 for any one to be hardy enough to call it in quef- 

 tion. Many refpedable and credible perfons de- 

 clare, they have not only beheld flocks of fwallows 

 colled and plunge into pools on the approach of 

 winter, but oftener than once have feen clufters 

 of them taken out of water, and even from be- 

 neath ice. The doubt therefore is, whether the 

 fwallows of which thefe refpedable authorities 

 fpeak are ours, that is, thofe conftruding an 

 earthen neft in our houfes, and refiding with us dur- 

 ing fummer, or whether they are ftrange fwallows, 

 by which I mean a bird fimilar in colour, figure, 

 and fize, but of a different nature and fpecies. 

 For many years I have endeavoured to folve this 

 queftion. Experiment has taught me, that ani- 

 mals which are torpid in winter become lethargic 

 alfo in other feafons, if fubjeded to the requifite 

 degree of cold ; fo that, on expofing a frog, a 

 dormoufe (^forcio mofcardino) or a lizard, to the 

 cold of freezing, in fummer, while mofl: vivacious, 

 it foon becomes torpid, and is in a flate of torpor 

 till the cold ceafes. Suppofing the fwallows of 



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