ming a dike across the stream, almost straight 
ere the current is weak, but where it is more 
id, curving more or less, with the convex 
opposed to the stream. They construct 
these dikes or dams of the same materials as 
hey do their lodges, viz. of pieces of wood of 
kind, of stones, mud, and sand. These 
Shag oppose a sufficient barrier to the 
eboth of water and ice; and as the willows, 
yoplars, &c. &c. employed in constructing them 
‘often strike root in it, it becomes in time a 
green hedge in which the birds build their 
_« By means of these erections the water is 
ept at a sufficient height, for it is absolutely 
ecessary that there should be at least three 
set of water above the extremity of the entry 
into their lodges, without which, in the hard 
frosts, it would be entirely closed. This entry 
§ not on the land side, because such an open- 
ng might let in wild animals, but towards the 
_ © They begin to excavate under water at the 
ise of the bank, which they enlarge upwards 
sraduaily, and so as to form a declivity, till 
hey reach the surface ; and of the earth which 
omes out of this cavity they form a hillock, 
with which they mix small pieces of wood and 
ven stones; they give this hillock the form of 
adome from four to seven feet high, from ten 
to twelve long, and from eight to nine wide. 
As they proceed in heightening, they hollow it 
ut below, sb as to form the lodge which is to 
receive the family. At the anterior part of this 
dwelling, they form a gentle declivity termina- 
_ fing at the water, so that they enter and go out 
under water, 
_ © The interior forms only a single chamber 
‘Tesembling an oven. Ata little distance is the 
azine for provisions. Here they keep in 
the roots of the yellow water-lily, and the 
nches of the black spruce, the aspin, and 
birch, which they are careful to plant in the 
These form their subsistence. Their 
gazines sometimes contain a cart-load of 
e articles, and the beavers are so industrious 
at they are always adding to their store.” * 
The nests so admirably constructed by what 
ave been called the perfect societies of insects, 
white ants or termites, the ants or formice, 
@ bees, wasps, and humble bees, are well 
mown, and have been often described. The 
terials used by the two first genera are chiefly 
» with bits of straw or wood, cemented by 
himal secretions ; the bees manufacture wax 
or the purpose. 
___ “ The wasps and hornets are remarkable for 
the well-known curious papier-maché edifices, 
_ inthe construction of which they employ fila- 
hents of wood, scraped from posts and rails 
h their own jaws, mixed with saliva, of 
ich the hexagonal cells in which they rear 
T young are formed, and often their combs 
Separated and supported by pillars of. the 
_ Same material ; and the external walls of their 
_ Rests are formed by foliaceous layers of their 
ligneous paper.” + 
* Kirby, vol. ii, p. 510. 
t Kirby, loe. cit, p. 335. 
Dl ee el 
INSTINCT. 
‘11 
“ The tree-ants, again, are remarkable for 
forming their nests on the boughs of trees of 
different kinds; and their construction is sin- 
gular, both for the material and the architec- 
ture, and is indicative of admirable foresight 
and contrivance ; in shape they vary from glo- 
bular to oblong, the longest diameter being 
about ten inches, and the shortest eight. The 
nests consist of a multitude of thin leaves of 
cow-dung, imbricated like tiles upon a house, 
the upper leaf formed of one unbroken sheet 
covering the summit like a skull-cap. The 
leaves are placed one upon another in a wavy 
or scalloped manner, so that numerous little 
arched entrances are left, and yet the interior is 
perfectly secured from rain. They are usually 
attached near the extremity of a branch, and 
some of the twigs pass through the nest. A 
vertical section presents a number of irregular 
cells, formed by the same process as the exte- 
rior. Towards the interior the cells are more 
capacious than those removed from the centre, 
and an occasional dried leaf is taken advantage 
of to assist in their formation. The nurseries 
for the young broods in different stages of 
developement are in different parts of the 
nest.””* 
What is most peculiar in the habitations of 
all these “ perfect societies of insects,” is the 
formation, by the same working members of 
these societies, of cells of different size and form, 
suited for the different classes or ranks of indi- 
viduals which, as we shall afterwards state, 
each of these associations comprises ; and the 
occasional alteration of the size and form of the 
cells, when circumstances occur, which will 
be afterwards mentioned, to make an alteration 
of their destination advisable. 
There are other examples among insects, of 
imperfect societies or associations, found tempo- 
rarily and during the larva state only, which 
unite in forming tents under which they feed, 
and which shelter them from sun and rain. 
This is done by the larve of several species of 
butterfly and moth.+ 
4. The next instincts which may be noticed 
under this head are those connected with the 
hybernation of animals ; for in almost every case 
in which this faculty (which is found so gene- 
rally in the lower tribes, particularly reptiles and 
insects, as well as in the order Cheiroptera and 
several others of the higher animals,) exists, there 
is attached to it some instinctive propensity, 
prompting the animal, even although it be not 
one of those which form houses for themselves, 
at least to search for some suitable residence in 
which it may be sheltered during the winter, 
whether under ground, under stones or timber, 
under the bark of trees, &c.; and it is very re- 
markable that their hiding places are often 
found, or formed, long before the weather has 
become very cold. “ I am led to believe from 
my own observation,” says Mr. Spence, “ that 
the days which the majority of coleopterous 
insects select for retiring to their hybernacula are 
some of the warmest days of autumn, when 
* Ibid. p. 340. 
¢ Spence and Kirby, vol. ii. p- 21. 
