REMARKS ON THE FIGURES OF PLATE XLI. 
THE ARCHETYPE COSTO-VERTEBRAL SERIES PERSISTS FOR THE THORACIC OR RESPIRATORY APPARATUS, 
JTANDARD plus quantity is never seen to vary from itself by addition or increase ; but all the variations 
which it undergoes, obey the law of subtraction. In this respect the creation of form differs from that 
of number ; for whereas number may increase by mental operation to an infinite degree, the creation of form 
by natural operation never passes beyond certain prescribed limits. A whole or integral form is fixed and of 
fmite character and dimensions. The thoracic whole quantity does not vary from itself by genetic or increasing 
changes ; but when, like the circle, it incloses space completely, it then may be said to have described the 
full sum of its development. As a whole quantity, however, this costo-vertebral thoracic figure may be said 
to contain an infinitude of variety ; and the law of metamorphosis or subtraction can subject it to all those 
degrees of minus variation. 
Every generalisation springs from comparative research. 
Every natural law is one of generalisation. Every natural 
Its character is the broad 
feature of simplicity; a myriad distinct facts are compre- 
law is one of simple operation. 
hended under one law; a myriad facts are all inter- 
preted as subservient to the law of gravitation; a myriad 
facts are gathered together under the common law of 
chemical affinity; a myriad anatomical facts become plainly 
interpreted under the law of unity in variety—plus ren- 
dered minus, plus subtracted from, the archetypes meta- 
morphosed, 
Fig. A, one of the quadrumanous species, may. be 
compared with itself, that is to say, its serial units may 
be compared to one another, and they will prove to be pro- 
portionals of an archetype, such as we find in the thoracic _ 
' region of series. They will prove that plus has been 
rendered minus, and that this is the only distinction to be 
drawn between two or more quantities of the serial skeleton 
axis. The terminal caudal ossicle 59 is a proportional of the 
penultimate caudal bone, this latter being a proportional of 
the next above it, and so we may follow from the quantity 59 
up through all the series of proportionals till we end at the 
thoracic archetype, thus advancing through the slow gra- 
dation of metamorphoses as through a series of arithmetic 
progression. 
Now we should distinctly understand, that as any two 
lesser proportionals of series cannot have been metamor- 
phosed from a greater third quantity which still actually 
exists, so must they therefore be interpreted as severally 
metamorphosed from their own archetypes, which are uni- 
form, and which have suffered varying degrees of meta- 
morphosis, in order to render those three minus quantities 
proportionally various to each other and to the archetype. 
Thus, when we say, that in fig. A, the first lumbar unit 
marked 21, is a proportional of the unit marked 20 a, we 
then mean that 21 has been metamorphosed from such as 
20 a, and so the orders of serial skeleton proportions and 
progressions prove themselves to be one and all as varying 
quantities degraded from a series of figures such as the 
thoracic. The terminal caudal quantity marked 59 fig. 
A, must hence be the proportional of a quantity such as 
we find to be the fullest: of thoracic series. 
In figs. A, B, and C, the same spinal units bear the same 
marks, and a comparison of any unit similarly marked in 
A, B, or C, will prove that these skeleton forms themselves 
are rendered proportionally various to each other by the very 
same process of metamorphosis which renders the serial 
units of the one skeleton axis proportionally various to each 
other.. Thus we see that in fig. C the skeleton axis of the 
sloth, its cervical unit 8 a, bears the same ratio to the unit 
below it marked 9 a, and this again to the first thoracic _ 
unit 10 a, which 9 a, of fig. C bears to 9a, of figs. B or A. 
Again, in fig. C we observe that unit 25 a, terminates the 
thoracic series below, and that unit 26 ais a proportional of 
the like quantity ; so, therefore, is unit 25 a, wherever it 
_stands in series for figs. B or A, to be regarded as the 
proportional of the like quantity 25 a, fig. C, and for the 
same reason that we take this latter to be a proportional of 
the thoracic archetype, so must we read all the units of 
series to be proportionals of the like archetypes. 
For evidently it is the subtraction from archetype plus 
which renders unit 59 fig. A thus degraded to the vanishing 
