imply that these habits necessarily belong to all
the individuals composing either of these divisions, for that would be
untrue, but simply that the figure of the pupils corresponds with that
frequently distinguishing day-roaming animals from those that prowl
only by night. It is remarkable that a more certain and serviceable
specific distinction is thus afforded by a little anatomical point,
than by any of the more obvious circumstances of form, size, or
colour. Whether future researches into the minute structure of animals
may not discover other means to assist the naturalist in
distinguishing nearly allied species, is a most important subject for
inquiry, which cannot be entertained here. But to encourage those who
may be disposed to undertake it, I must mention the curious fact, that
the group to which the camel belongs is not more certainly indicated
by his grotesque and singular figure than by the form of the red
particles which circulate in his blood. And here again the inherent
interest of the matter will lead me to enter a little into
particulars, which may engage any one who has a good microscope in a
most instructive course of observations, not the least recommendation
of which is, that a just and pleasing source of recreation may be thus
pursued by evening parties in the drawing-room, since the slightest
prick of the finger will furnish blood enough for a microscopic
entertainment, and you may readily procure a little more for
comparison from any animal.

Now the redness of the blood is owing to myriads of minute objects in
which the colour of the vital fluid resides. They were formerly called
globules, but as they are now known to be flattened and disc-like,
they are more properly termed particles or corpuscles. Their form is
wonderfully regular, and so is their size within certain limits; in
birds, reptiles, or fishes, the corpuscles are oval. They are circular
in man, and all other mammalia, except in the camel tribe, in which
the corpuscles are oval, though much smaller than in the lower
animals. Thus, in the minutest drop of blood, any one of the camel
family can be surely distinguished from all other animals, even from
its allies among the ruminants; and what is more to our purpose,
in pursuing this inquiry, Mr. Gulliver has found that the
blood-corpuscles of the dog and wolf agree exactly, while those of all
the true foxes are slightly though distinctly smaller.

These curious facts are all fully de