16 On the present state of Zoology. 
the existence of such a plan belongs to a much earlier period than the 
present ; and that Linnaeus, and even the older naturalists, had some 
faint notions upon this subject ; but, until the close of the last century, 
there was hardly any attempt made to elucidate its principles ; and 
only quite recently has this attempt, with some few exceptions, be- 
come general. The reason is obvious. The science had not made 
sufficient progress to warrant the endeavour. And for the same rea- 
son, it is obvious we must await the arrival of many years to come 
before we can hope to see that endeavour perfected. We are not, 
then, surprised to find, that although naturalists are everywhere pur- 
suing the same object, they are following very different roads in 
the hope of attaining it. We should wonder if it were otherwise. 
When we think of the immense field which Zoology lays before 
us, of the comparatively small portion of that field as yet explor- 
ed, and of the impediments which arise to make our path diffi- 
cult ; when we reflect further, how much is required to determine the 
exact relations of a single group, and how often we are left to mere 
conjecture and analogy, in the absence of facts, which can alone esta- 
blish our reasonings on a sure basis ; we are prepared to meet with 
much variety of opinion upon such a subject. It is, indeed, more than 
probable that the classification of animals is destined yet to undergo, 
at least in part, great and important changes.* The views of natu- 
ralists will differ, according as they have paid most attention to this or 
that department of the science, in each of which, from the unequal pro- 
gress of our knowledge, we appear to recognize the influence of dis- 
tinct principles. Their minds, too, will receive, unconsciously to them- 
selves, a slight bias, arising from the nature of their other studies, or 
of those which led them to the particular study of which we are here 
speaking. It is only time which can do away with the erroneous con- 
clusions of a partial or a prejudiced judgment. Contrariety of opinion 
originating in the above sources, is for a season unavoidable ; and we 
must wait patiently till we have received sufficient light to determine 
those questions, with respect to which naturalists are so much at issue. 
But independently of what has been above-mentioned, there is ano- 
ther and distinct ground of difference observable in the attempts which 
have been made of late years to arrange animals upon some uniform 
plan. In fact, as has been recently said,f there are two distinct prin- 
* We may mention in this place, that a new arrangement of the Animal King- 
dom has been recently brought forward by Professor Ehrenberg of Berlin. It is 
divided into 29 classes founded on the organization, and on the general existence 
of one type of structure, as respects the system of sensation, circulation, locomo- 
tion, nutrition, and reproduction See L'Institut, 1835, p. 305. 
f Lam. Hist. Nat. des An. sans Vert. (2d edit. 1835.) torn. i. p. 336. 
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