526 
& 
snow-storm. IT should rather think too 
that the white weasel, which is seen ir 
the south of Scotland, is not the same 
species with that which is common in the 
Island of Lismore. But whether there is 
a species of this animal, which, like the 
mount hare, changes its colour with 
the change of season, or whether it is on- 
ly a variety of the Mustela vulgaris, 
which is found in Lismore, I have not 
been able to determine, I am certain 
that the common weasel does not always 
change its colour, as I have frequently 
seen them of their ordinary brown here 
during winter. I am not certain that a 
brown weasel has ever been seen, during 
the cold season, in the Island of Lismore, 
or that a white one had ever been ob- 
served insummer. 1 should he extreme- 
ly happy to have the observations of 
some of your correspondents on this sub- 
ject, and particularly with regard to the 
different species or varieties of the wea- 
sel, which are, or have been, observed in 
this country. 
' There are one or two other animals, 
Sir, which I might enumerate here as ex- 
hibiting a considerable change in their 
colour at different seasons, but I shall 
conclude this part of these remarks with 
a few observations on the Ptarmigan, the 
(Tetrao Lagopus of Linné). 
This bird, which is rather larger than 
the common partridge, is found in the 
north andwest of Scotland,in considerable 
quantities, particularly in the [ebrides, 
It is amongst the most stupid of all birds, 
for if a stone or snow-ball is thrown so 
as to fall near it, you may go up and 
knock it dead with a stick, as ‘+ anpears 
s0 much astonished, that it seldom at- 
tempts to fly away. They never attempt 
to fly ina high wind; and except in the 
Jatter end of summer, we seldom meet 
with two or three of them together. 
They frequently build their nests under 
the snow, and are always found on the 
shaded sides of the mountains. But I 
mention this bird chiefly on account of 
the change of colour, which its feathers 
undergo. 
During summer the ptarmigan is not 
easily distinguished from the partridge at 
a distance, as the colour of the feathers 
isso much alike in both. But in winter 
the whole of the feathers of the ptarmi- 
gan, except two, are of a pre white. 
These two feathers, which are in the tail 
of the bird, remain of a black colour both 
- $amrner and winter. 
fi this change of colour in the animals 
which I have mentioned, we see a beau- 
On the Change of Colour in Animals. ° 
~ [Jan 1, 
tiful provision of nature, in which the 
wisdom and goodness of the creator are 
equally conspicuous. This change is 
both a source of security and ofadditional 
comfort to the animals. The timid and 
short-lived hare is not only persecuted 
by lordly man, but is equally preyed 
upon by the wolf, the fox, the hawk, 
and the eagle ; and the more they are se- 
cluded from the haunts of men, the more 
liable they are to be destroyed by these 
last-mentioned depredators; and had 
they remained of a dark colour, while 
the mountains were covered with snow, 
they could not have stirred abroad, with- 
out being exposed to certain destruction ; 
but by the change which as [ have shewn 
takes place in their colour, and particu- 
Jarly in the mountain hare, they are not 
so easily discovered by the hawk or hun- 
gry eagle. The same remark applies to 
the weasel and ptarmigan; they too are 
preyed upon by the hawk and eagle. 
But if the security which this change of 
colour gives the animals is great, the 
comfort which accompanies it is not less 
wonderful. It is particularly observed, 
that as the down becomes white, it be- 
comes also of a much finer texture ; and 
modern chemistry has taught us that fine 
down is a very slow conductor of heat, 
and that the finer the down, the less is its 
conducting power ; while:it is also ascer- 
tained, that white and shining surfaces 
tend very much to retard the egress of 
heat from any body. These cireum- 
stances, as I have said, Sir, are very evi- 
dent; but the manner in which this 
change of colour is brought about is not 
so apparent. I shall, therefore, conclude 
this short paper with a few observations 
on the structure of the common integu- 
ments, but chiefly of the hair and fea, 
thers, with a view, if possible, of throw- 
ing a little light on this part of the sub- 
ject. 
Each hair consists of a bulb and a 
stalk, and sometimes, as in long hairs, 
of branches. The bulb is placed in the 
cellular membrane, under the true skin, 
and consists of two vesicles and. a nu- 
cleus. ‘The nucleus appears to be a 
quantity of fibres, coiled up; but between 
each vesicle there is a small quantity of 
fluid. 
The stalk of the hair consists of a corticle 
or bark, a cortex, and medulla, or pith. 
The corticle and cortex are derived 
from the vesicles of the bulb, and have 
always a small quantity of fluid betwixt 
them. The pith is composed of parallel 
fibyils, which are derived from the nu- 
cleus 
