14 
INTRODUCTION. 
touching with their fragile wings the hard surface of the 
never-melting snow. The gigantic condor or vulture of the 
Andes has been seen to soar on its widely-expanded wings 
far above the highest peak of Chimborazo, where the baro¬ 
meter would have sunk below ten inches. The existence of 
marine fishes has been ascertained at a depth of from 500 to 
600 fathoms; and in the deep recesses of those caverns in 
Styria and Carniola, which are inhabited by the curious 
Proteus (Zool. § 532), numerous species of insects are found, 
all of which, however, like the Proteus, are blind. 
Having thus glanced at some of those facts which demon¬ 
strate the practical importance of the study of Physiology, 
and having indicated ’ the mode in which that study should 
be pursued, it remains to offer a few observations upon its 
value with reference to the culture and discipline of the 
mind itself. One of its great advantages is, that it not 
only calls forth, in a degree second to no other, both the 
observing and the reasoning powers; but that it offers so 
much that is attractive by its novelty to those who enter 
upon it seriously, and make it an object of regular pursuit. 
For it affords abundant opportunities, even to the beginner, 
of adding to the common stock of information respecting the 
structure and habits of the vast number of living beings that 
people our globe. The immense variety of the objects which 
come under the investigation of the physiologist, so far from 
discouraging the learner, should have the effect of stimulating 
his exertions, by opening to him new fields for productive 
cultivation. Of by far the larger part of the organised crea¬ 
tion, little is certainly known. Of no single species,—of 
none of our commonest native animals,—not even of Man 
himself,—can our knowledge be regarded as anything but im¬ 
perfect. Of the meanest and simplest forms of animal life, we 
know perhaps even less than we do of the more elevated and 
complex ; and it cannot be doubted that phenomena of the 
most surprising nature yet remain to be discovered by patient 
observation of their actions. It was not until very recently, 
that the existence of a most extraordinary series of metamor¬ 
phoses, more wonderful than those of the insect, has been 
discovered in the jelly-fish of our seas, in the barnacles that 
