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2 REMARKS ON THE FIGURES OF PLATE III. | 
spine are not continued in series from the exogenous 
transverse processes 1, 2, 3, 4, of the dorsal spine. These 
latter processes at 4 pass backwards and are continued 
into the lumbar exogenous tubercles. The close examina- 
tion of any human spinal series will prove the truth of 
this observation, and much will be afterwards seen to de- 
pend upon our establishing clearly the distinctive character 
between the serial processes 1, 2, 3,4, and those processes 
marked a, b, ¢, d, e,f. 
The serial order in which spinal figures are developed 
is fully expressive of the homology of their form and ele- 
mental parts. Every vertebra of the same series is known 
to contain some structural quantity, (more or less,) which 
is repeated in the vertebra preceding and succeeding 
itself, and it is not possible for the anatomist to separate 
that form from spinal series which may be said to present 
any other variety than that which occurs by the subtrac- 
tion of quantity. A series of forms is a succession or 
continued order of homologues repeated—it is a line of 
things created similarly and uniformly. Whenever we 
find an exception to this lineal uniformity, such exception 
is caused by an absence or negative condition of some 
elemental part of one of the figures of series. A hiatus or 
subtraction of quantity may dismember the continuity of 
the serial uniform line, but Nature never introduces in the 
stead of that lost quantity, any other thing of absolutely 
dissimilar kind. 
In fig. A we see the serial order of the several elementary 
pieces proper to vertebral quantity. Spimous processes 
hold serial relation to each other from occiput to sacrum. 
Neural arches manifest the order of lineal series also. 
The bodies of vertebre in fig. B in like manner are con- 
tinued in series from the basilar processes of the occipital 
bone, to the last caudal nodule. These three orders of 
elemental structure are dissimilar to each other. The one 
serial order of elements is never confounded with, or lost 
in the other; they are created as separate entities, in sepa- 
rate localities, and they always hold separate. They are 
parallel lines of distinct structures, and when we see 
that either line declines, by process of subtraction, we still 
never find that the vanishing point of one series is the 
genetic point of another. 
But in each of these three series of distinct parts, in 
that of spinous processes, of neural arches, and of bodies 
of vertebree, we find that the line of which each is com- 
posed, is the simple repetition of that structure proper to 
each line; and although we at once recognise the dis-~ 
tinctness which characterises the structures of one line 
from those of the other, yet we cannot thus characterise 
distinctness or variety between the serial pieces of the one 
line. The spinous process, the neural arch, and the ver- 
tebral body, are structural varieties, and the series produced 
by the repetition of each of these structures is a various 
series, compared with the other two; but every elemental 
piece found in one serial order is the homologue of all 
other pieces of that same order, and in this order there 
happens no other condition of variety than that of plus 
and minus quantity. The spimous processes of the sacral 
vertebree are only minus when compared with the spinous 
processes of the lumbar vertebre. The caudal centrums 
are only minus quantities compared with the lumbar 
centrums of the vertebre. 
Two series of distinct structures are never found to flow 
into one another. Anatomy has never yet experienced the 
fact of a neural arch occurring where vertebral centrums 
hold serial relation. Nature is order as well in the micro- 
cosm of her infinitesimals as in her planetary location, 
and neither does the series of processes marked 1, 2, 
3, 4, 5, 6, 7, im fig. A confound itself with the parts of 
that distinct series marked a, 6, c, d, e, f. 
The serial order of vertebral quantities, as well as the 
serial orders of those distinct elements which are found in 
those quantities, may be contemplated in the same idea 
which science entertains of an animal kingdom, namely, 
that “the law of continuity requires that all natural bemgs 
should form a single chain.” * The law of continuity is 
the law of series, and both are synonymous with the 
existence of linear homologues. Form is an ens, and the 
repetition of this is the creation of series or uniformity. 
The exception to uniformity is the absence of some 
known quantity which leaves the ens minus in relation 
with the ens plus. The processes marked 1, 2, 3, 4, 5, 6, 
7, are continued in a line of plus and minus quantities 
from occiput to the sacral dorsum; but the processes 
marked in rising order from f to a, hold their own serial 
position, and become suddenly interrupted at a, not by 
natural subtraction of quantity, or graduated metamor- 
phosis of structure, but by our own mechanical dismem- 
berment of parts which are created continuously with a in 
full skeleton quantity, as will be hereafter shown. 
* Leibnitz—L’appel au public de Kenig. Lettres. 
