2 
LIFE. 
so elaborately constructed, as to deserve to be included in 
the category of those works which the adoring Psalmist 
says are great. 
We propose in this volume to describe the various 
phases of animal life, commencing at the foot of the scale, 
whei-e wo catch the first glimmering of the vital spark, 
and tracing it step by step upwards through its various de- 
velopments and changes, its forms and functions. But what 
is life 1 There is a mystery couched under that little word 
which all the research of philosophers has not been able 
to solve. Science, with the experience of ages, with all 
the appliances of art, and with all the persevering inge- 
nuity and skill that could be brought to bear upon it, has 
ardently laboured to lift tho veil; but philosophy, and 
science, and art, stand abashed before the problem, and 
confess it a mystery still. The phenomena, the properties 
of life, are readily observable. We take a bird in our 
hands; a few moments ago it was full of energy and 
animation ; it shook its little wings as it hopped from 
perch to perch ; its eyes glanced brightly, and its throat 
quivered as it poured out tho thrilling song which de- 
lighted us. Now the voice has ceased, tho eye is dim, the 
limbs are stiffening, and we know that it will move no more. 
Chemical changes have already begun to operate upon its 
organs ; decomposition is doing its work, and soon the 
beautiful little bird will be a heap of dust. We say that 
its life has gone ; but what is it that has gone 1 If we put 
the body in the most delicate balance, it weighs not a 
grain less than when it was alive ; if we measure it, its 
dimensions are precisely the same ; the scalpel of the 
anatomist finds all the constituent parts that made the 
