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REMARKS ON THE FIGURES OF PLATE XIII. | 3 
vertebra; and this is enough to know in furtherance of the 
present argument. The proportional, however small it 
The caudal 
bone, however small it may be, compared to other quanti- 
ties of the same series, is still the caudal proportional of a 
vertebra—and hence the common median line which 
-severs symmetrically this caudal quantity, bisects at the 
same time the ideal form of that vertebra of which it is a 
proportional. Hence, also, when we carry the horizontal 
line 5 transversely across the series and examine the exist- 
ing serial quantities above and below it, we well know that 
if a caudal ossicle, which terminates inferior series, be not 
equal to that form which commences superior series, or to 
that which may be found in any other region of the same 
continuous line, still it is not various to its fellows in series 
by any other condition of development save that of being 
a minus proportional of its own plus form, which, if we 
were required to imitate, might be done according to the 
fashion of any of its existing serial analogues. ~ 
Before proceeding any further in the development of our 
present views, it becomes absolutely necessary to state in 
plain terms what those opinions are to which our anatomical 
facts of comparison shall never lead us. The interrogative 
sentiments which anatomists of the school of Cuvier have 
put forth triumphantly against the doctrine of absolute 
uniformity, are as follow :—They ask, “ Y a-t-il unité de 
structure ?”—“ Y a-t-il unité de composition ?”—“ Y a-t-il 
unité de type ?’—“ Y a-t-il unité de plan?” If, say they, 
you mean to support your views of uniformity according to 
may be, is still the proportional of an integer. 
the affirmation of either of these questions, then demon- 
strate to us the identity between a polype and a cephalopod, 
between either of these two and a whale.* These requisites 
for the illustration of nature’s uniformity, we at once eman- 
cipate ourselves from promising to supply, and indeed it 
may be doubted whether the pleasantry occasioned by the 
proposition demonstrated ad absurdum attaches more to the 
question asked than to the position sought for, and though it 
be still most true that the analogists have turned back on 
classifiers the cannonry of their own argument in defiance 
of their classification according to absolute difformity, still 
we shall continue to pursue the present subject in its own 
distinct course, believing that the difference which exists 
between a structural plus and minus quantity cannot suffer 
them to be named absolutely equal and uniform in this 
sense, even though they be bound together by the zone of 
Newton and unity. Neither by the existence of the same 
facts of plus and minus proportioning, can the difference - 
between two such quantities allow of their being read as 
species in the sense of an absolute difformity of nature, 
even if they were separated from each other by an interval 
sufficient to receive all the volumes of Cuvier written to 
that end. If we admit that the law of proportioning is that 
whereby skeleton forms are varied from each other, then 
we may reasonably make effort to determine, by the facts 
of comparison, what is the character of that plus or arche- 
type form which suffers metamorphosis or proportioning. 
And such is our immediate purpose. 
* “ Qui osera,’’ demands Cuvier, “‘nous dire que la méduse et la girafe, que l’éléphant et V’étoile de mer, résultent d’un assemblage de 
parties organiques qui se répétent uniformément.” To this question Geoffroy replies that, “Il y a une confusion manifeste dans les raisonnemens 
de l’argumentation ; et cette confusion me parait méme portée 4 son dernier terme, quand, ne s’appliquant point a discerner les divers degrés de 
Vorganisation, ’argumentation demande qu’on lui fournisse ipso facto les rapports immédiats de la méduse et de la girafe, de l’éléphant et de 
V’étoile de mer. Un tel @ fortiori n’arrive sans doute point 1a en desespoir de cause. Je regrette véritablement de rappeler cette expression. 
Cet a fortiori n’est probablement qu’une négligence échappée 4 la plume de mon savant confrére. La phrase a fait, je crois, sourire quelqu’un 
dans V’assemblée ; mais, je le suppose du moins, elle n’aura porté de conviction dans aucun esprit.’”—See Principes de Philosophie Zoologique, 
discutés en Mars 1830, au sein de ? Acad. Roy. des Sciences. Par Geoff. St. Hilaire. 
