132 General Notes. [ February, 
occurred in the great Marshes of Lake Erie. During a severe 
winter the mud and water froze to a great depth. The conse- 
quence was that when the marshes thawed out the shallows were 
covered with dead turtles, snakes, frogs, etc. The unanimous 
opinion of the Corps of Engineers was, that the cause of this whole- 
sale slaughter of the reptiles was some poison permeating the 
marshes, doubtless generated by the slow approach of spring. 
There may be such a thing as being frozen too effectually, how- 
ever, for a good condition of torpidity. Asa final instance I may 
note the return of frogs from their winter’s quarters, at Camden, 
N. Y. Hundreds of these near this place came up from the earth 
in a shallow marsh, tumbling, leaping, and capering about, some 
of them appeared belly up, others with huge bags protruding 
from their mouths. They were ail in a weak, half-sensible state, 
but gradually regained strength in the sunlight. 
It is evident that animals do not assume a torpid state in warm 
weather, since no instance of the kind is known or recorded. 
he above instances seem therefore applicable to the previous 
conclusion that animals in a torpid state may be aroused by an- 
increase of temperature, or in other words, torpidity is but a low- 
ered temperature, sometimes to the freezing point. — William 
Hosea Ballou. 
‘MicrAtTion oF Dracon Fiirs.—On the 2d of June, in Wey- 
mouth, Mass, I observed what seemed to be a concerted migra- 
tion of dragon flies, and should be glad to be informed whether 
such movements are of regular occurrence, and if they are, what 
is the explanation of them? I was sitting in a pasture near the 
edge of a wood (the wood being, perhaps, half a mile deep), at 
about eight o’clock in the morning, when I first became aware 0 
what was going on. e flies came from over the trees, and 
generally on reaching the pasture, dropped to within five or ten 
feet of the ground, although many flew much higher and some 
went straight across the pasture at an estimated height of forty 
feet. All, with rare exceptions, kept a steady course due west, as 
though they were moving to some appointed rendezvous. They 
came in sight somewhat as waves come upon the beach—one 
minute there were none, and the next there were two or three or 
half a dozen together. I watched them for three hours or more, 
and in the afternoon followed in their train across two roads and 
some pasture lands to the edge of another wood. When they 
reached this wood they seemed, many of them, a little at a loss 
how to proceed, but soon mounted into the air and sailed over 
the trees out of sight. I then visited a small pond in the vicinity 
and took notice that they flew across it and kept on in their 
westerly course. As to the width of the column, I only know 
that it was at least a quarter of a mile. They were still flying at 
a little before eight o'clock in the evening, when it was almost cued a 
