9 . REMARKS ON THE FIGURES OF PLATE VII. 
When the eye follows the transitional change which 
Nature exercises upon origina] serial uniform quantities, 
such as appear in the spinal axis, the opinion which arises 
respecting this particular is as follows, viz., that the primi- 
tive cast of such a series is uniformity, and that the variety 
is not absolute, but only as it were resulting by an after- 
It is unity itself which 
undergoes this modification, and thus there cannot happen 
thought for special modification. 
in the one series any gap or abrupt differencing between 
form and form. The law of Nature operates in gentle 
gradations through a serial line. Forms which stand far 
apart in the same linear arrangement may present examples 
of almost unallied specialty, and in such distinctiveness as 
almost to mask the original features of sameness, but 
nevertheless we find (between two such extremes) the 
things of transition and easy passage—the things of fluxion, 
which render series as a oneness, and defy contrast by the 
imperceptible interchange of character. As it is through 
the serial line of an animal kingdom, so we find it in the 
serial line of vertebral quantities. 
A single vertebra cannot be isolated from its fellows in 
series, and pronounced to be absolutely difform to any 
other quantity of that series. If one vertebra compared to 
another manifests some modification, and demands there- 
fore the name of species, then species is but modification. 
If, again, an entire class of vertebral quantities compared 
to another class expresses some condition of modification, 
and requires therefore to be classified separately, then 
classification is based upon metamorphosis or modification. 
And he who would follow organic metamorphosis in quest 
of the end of that subject of classification according to 
distinctiveness of animal character, is like one who would 
seek to isolate a portion of time, or space, or number 
from all time, all space, and all number. 
The vertebrz of transition between classes of vertebrae 
are like the animals of transition between classes of 
animals—they connect and enchain forms in one con- 
tinuous series, and by their own equivocal character they 
defy all method, and render it an uncertain opinion.* 
Forms which are created serially within the animal cannot 
admit of classification as things absolutely distinctive. 
And forms which are developed serially within the 
abstract animalty do not permit of classification as things 
of absolute dissimilarity. 
The law of Continuity is 
creative of those entities which are continuous in a line. 
And this line, whether it be drawn of vertebral or of 
animal quantities, is only varied throughout its length by 
the subtraction from plus form, and is rendered finite by 
the same process. Thus we have fig. D’”” at the termina- 
tion, and fig. A” at the origin of vertebral series, just as 
we have a polype and an elephant at opposite extremes of 
the animal series. 
The forms of series are cast-in the same mould. Verte- 
bree of the same series give examples of a common analogy. 
This analogy is so positive a condition of these forms, that 
it is still evident amongst them even when degradation 
renders them as unequal things or quantities. The law of 
serial order compels us to name even things of unequal 
quantities under a common title, and thus it happens that 
we give to figs. A” B”C” and D”” the general name of 
vertebre. But as it cannot be understood that this name 
“vertebree”’ implies equality as to quantity (for no one shall 
undertake to demonstrate the whole quantity of A”, or B”, 
or C’, in D’”), and furthermore, as it cannot be denied 
that fig. D’” refers to a certain known part of either fig. 
C”, or B”, or A”, which part is no other than the centrum, 
so we say that all facts and ideas springing from the com- 
parison of fig. D”” to any other quantity in serial order 
with itself, must inevitably draw forth the conclusion that 
fig. D’” has been metamorphosed from a quantity equal to 
the fullest quantity created in the series. 
Any series of quantities which form an uninterrupted 
line, and which vary from one another only by excess and 
defect, such as vertebree, may have the phrase unity of plan — 
applied to it without implying also a unity of number as to 
the elemental parts persistent for each form. And hence 
those forms of series which manifest no other variety 
amongst themselves than that of quantity, cannot be said 
to vary from serial uniformity otherwise than by quantity. 
Any classification of such forms must therefore be according 
to the differential quantities between them. But as this 
quantity may vary from plus amount to a microscopic 
molecule, or even a thing of lesser bulk, so will we for ever 
find that classification based upon the differential law is a 
subject without end. 
ois : r E : oC 
* Transition-figures occurring between two classes of a continued chain of forms, have called forth the following remark, viz., “ Toutes les 
espéces qui occupent les régions d’énflewion et de retroussement devant étre équivoques et douées de caractéres qui se rapportent également aux 
espéces voisines. IJ] est méme convenable a l’ordre de la nature qu'il y en ait.” —Lettres de Leibnitz. 
