pid or other ftate, during the winter-feafon, feems rather to ftrengthen, than to weaken, the argument, that thefe 
birds are, in general, migratory birds. If all thefe birds continued among us, many of them would be found. 
The labours of one century, or more, in cutting down the timber of the foreft, in blowing rocks, in draining mill¬ 
ponds, and marfhes, would furnifh more than five or fix inftances (and they not always quite fo well authenti¬ 
cated as we could wifh) of Swallows, occ. being found during the winter-feafon, in a benumbed date. 
§. XXVIL 
The argument derived from the torpid date into which fo many of our animals arc obferved to fall upon the ap¬ 
proach of winter, is of lefs weight than may, at firft fight, be imagined. Thefe animals are much lefs capable of 
migrating than the birds. If they were capable of making long journies to more favourable climates, I do not doubt 
they would make them. For I am perfuaded, by a variety of experiments and obfervations which I have made, and 
may, perhaps, be induced to communicate to the public at fomc future period, that mod of our hybernating ani¬ 
mals go with reludance into this date. I am even of opinion, that the date of torpidity of many animals is a date 
of pain and fuderance. This obfervation, at lead, feems to hold good with refpe£l to thofe animals (and I believe 
they conditute the greater number of the hybernating animals) which divide the winter between deeping and wak¬ 
ing : which, in other words, under the induence of cold and other caufes, fall into a kind of profound deep, during 
which the functions of the heart and the lungs are condantly performed; and even that of the domach and intef- 
tines, in fome mcafure, goes on : and during all which time, fuch animals are fenfible to the induence of mecha¬ 
nical and other dimuli. This clafs of hybernating quadrupeds often, during the courfe of the winter, fpontaiieoudy 
awake from their dumber, take food, and fall into dumber, again. I do not, however, imagine, that animals, which 
are fo torpid as to be incapable of being roufed by the application of the mod powerful dimuli, can be faid to be in a 
date of pain and fuderance. But I believe, that the number of thefe continual deepers is very fmall, even in the 
colded climates. 
§. XXVIII. 
We are certain, that the torpid date of many animals is altogether an accidental circumdance: that is, it is not 
necedary to the fpecies. I will not affert, with my learned and ingenious friend, Mr. Fabricius, that it is nqt natural 
to, nor coeval with, the fpecies. It would be difficult to prove this pofition : but the pofition which I have advanced 
may be maintained. Animals of the fame fpecies have often a very extenfive range over the world. Thus, the Urfus 
Lotor, or Raccoon, extends from Lake-Superior to the Wed-India-Idands, and the warm parts of South-America. 
The Opodum has a range not much lefs extenfive. I trace the Rattle-Snake (Crotalus horridus) as far north as the 
Bay of Saguena, on Lake-Huron, and it is known in the country of Brafil. In fuch extenfive trads of country, thefe 
animals are expofed to very different degrees of temperature : on the one hand, to a great alternation of heat and 
cold; on the other hand, to a perpetual fpring and dimmer. We ought not, therefore, to expe£l: to find any of 
them torpid in the whole of this extenfive range. In faft, feveral of thofe animals which become torpid in the 
northern parts of our country do not fall into this date in the fouthern and warmer climates.* As cold, however, 
is not the only caufe of the torpidity of animals, we mud not be furprized to find indances of animals becom¬ 
ing torpid in climates that are warm. Extreme heat, like extreme cold, feems to predifpofe the animal fydem to 
this date, particularly, perhaps, when there is a deficiency of food. 
§. XXIX. 
We fee that quadrupeds and fome other animals do occafionally, during fevere winters, migrate to more fouthern 
climates. I am affured, that the Bears migrate, in great numbers, every autumn, acrofs the Miffiffippi, going fouth 
(perhaps to the mountains of New-Mexico), in fearch of a milder climate. In the fpring, they return again by 
• Sec my account of the Dipus Americanus, or American Jerboa, in tlie 4th volume of the Tranfadions of the American Philofophical Society. 
