‘ 
EXTENSIVE GENERA FAVOURABLE FOR STUDY. 219 
for so the wide intervals between the objects they 
contain proclaim them to be, — may be set aside for 
future analysis, when we have attained to higher 
degrees of inductive generalisation. It is those 
genera which, from containing numerous species 
and modifications of form, are usually termed per- 
fect, which we are more especially to select as fit 
objects for the preceding line of enquiry. We all 
know, that the more numerous and varied are the 
materials given to us for accomplishing a given 
work, the greater will be the degree of accuracy 
attending the result, provided we use these materials 
for the purposes for which they were designed, and 
make each fit into the other with symmetry and 
order, so as to produce a perfect whole. Applying 
this to the question before us, we may safely assume 
that extensive genera are the most calculated to 
elicit the first principles of classification. They 
seem as if intended for natural storehouses, wherein 
we should find all sorts of implements with which 
we may try our hand at combining, changing, and 
remodelling, until we make all the parts, like those 
of a complicated puzzle, fit into each other; and 
produce, from what appeared a heterogeneous as- 
semblage of isolated objects, a perfect tablet of 
order and beauty. It must be confessed, indeed, 
that such genera are the plague and torment of 
those who seek only to arrange them artificially ; 
because the interchange of characters is so gradual, 
and the intervals between the more prominent types 
so filled up and crowded by connecting species, that 
it seems utterly impossible where to make one 
division begin, or where end. It is clear, however, 
