John Carr - "The Stranger in France"

John Carr - "The Stranger in France"

Charlotte Mary Yonge - "Cameos from English History, from Rollo to Edward II"

Friedrich Hebbel - "Agnes Bernauer"

Annual Bibliography of Commonwealth Literature 2007
This paper argues that discourses of love in Ghanaian market literature for youth offer a view into complex negotiations of agency and empowerment. Drawing on Deborah Durham's notion of youth as "social `shifters'" and Francis Nyamnjoh's conception of the "interconnectedness" of agency, I take Ghanaian market literature as one specific case of how African literature for youth foregrounds questions of continuity and change as African societies enter into increasingly complex global relations. In this literature for youth, received notions of love, often constructed out of impressions from American pop and hip hop music, carry new notions of agency that compete with existing "domesticated" forms. Authors like Ike Tandoh and Evelyn Tay employ discourses of love to offer youth alternative avenues for empowerment in a context of socio-economic disenfranchizement. In a creative process of "straddling", this writing both reveals and reproduces the contradictions that obtain in youth configurations of agency.

Form and Function

E >> E. S. (Edward Stuart) Russell >> Form and Function




The enterocoelic theory was taken up by O. and R. Hertwig as an
essential part of their _Coelomtheorie_.[447] In a lengthy series of
monographs these workers made a comparative study of the mode of
formation of the middle layer, and arrived at a coherent theory of its
origin. They distinguished in the middle layer two quite distinct
elements, the mesoblast proper, formed by the evagination of the walls
of the archenteron, and the mesenchyme, formed by free cells budded off
from the germ-layers. The following passage gives a good idea of their
views and of the phylogenetic implications involved:--"Ectoblast and
entoblast are the two primary germ-layers which arise from the
invagination of the blastula; they are always the first to be laid down,
and they can be directly referred back to a simple ancestral form, the
Gastraea; they form the limits of the organism towards the exterior and
towards the archenteron. The parietal and visceral mesoblast, or the two
middle layers, are always of later origin, and arise through evagination
or plaiting of the entoblast, the remainder of which can now be
distinguished as secondary entoblast from the primary. They form the
walls of a new cavity, the enterocoel, which is to be regarded as a
nipped-off diverticulum of the archenteron. Just as the two-layered
animals can be derived from the Gastraea, so can the four-layered animals
be derived from a Coelom form. Embryonic cells, which become singly
detached from their epitheliar connections we consider to be something
quite different from the germ-layers, and accordingly we call them by
the special name of mesenchyme germs or primary cells of the mesenchyme.
They may develop both in two-layered and in four-layered animals. Their
function is to form between the epithelial limiting layers a secreted
tissue (_Secretgewebe_) or connective tissue with scattered cells, which
cells can undergo, like the epithelial elements, the most varied
modifications.... This secreted tissue in its simple or in its
differentiated state, with all its derivatives, we call the mesenchyme"
(p. 122).

The important point for us is that, just as all Metazoa were considered
by Haeckel to be descended from the Gastraea, so all Coelomati were held
by the Hertwigs to be derived from an original coelomate _Urform_. In
both cases an embryological archetype becomes a hypothetical ancestral
form.

The Coelom theory was considerably modified, extended and developed by
later workers, particularly as regards the relations to the coelom of
the genital organs and ducts and the nephridia, but no special
methodological interest attaches to these further developments.[448] We
shall here focus attention upon one interesting line of speculation
followed out in this country particularly by Sedgwick--the theory of the
Actinozoan ancestry of segmented animals. Its relation to the Coelom
theory lies in the fact that Sedgwick regarded the segmentation of the
body as moulded upon the segmentation of the mesoblast, which in its
turn, as Kowalevsky and Hatschek had shown, was a consequence of its
mode of origin as a series of pouches of the archenteron. In other
respects Sedgwick's speculations link on more closely to the Gastraea
theory, for one of his main contentions is that the blastopore or
_Urmund_ is homologous throughout at least the three metameric phyla. In
following up Balfour's observations on the development of
_Peripatus_,[449] Sedgwick was struck with the close resemblance existing
between the elongated slit-like blastopore of this form (giving rise to
both mouth and anus), with its border of nervous tissue, and the
slit-like mouth of the Actinozoan (functioning both as mouth and anus),
round which, as the Hertwigs had shown, there lies a special
concentration of nerve cells and nerve fibres. He found another point of
resemblance in the gastric pouches of the Actinozoa, which he
homologised directly with the enterocoelic pouches of the Coelomati. He
was led to enunciate the following theses:--[450] (1) that the mouth and
anus of Vermes, Mollusca, Arthopoda, and probably Vertebrata, is derived
from the elongated mouth of an ancestor resembling the Actinozoa; (2)
that somites are derived from a series of archenteric pouches, like
those of Actinozoa and Medusae; (3) that excretory organs (nephridia,
segmental organs) are derived from parts of these pouches which in the
ancestral form, as in many polyps, were connected by a circular or
longitudinal canal, and opened to the exterior by pores. This
longitudinal canal was lost in Invertebrates, but persisted in
Vertebrates as the pronephric duct, while the pores remained in
Invertebrates and disappeared in Vertebrates; (4) that the tracheae of
Arthropods, as well as the canal of the central nervous system in
Vertebrates, are to be traced back to certain ectodermal pits in the
diploblastic ancestor comparable to the sub-genital pits of the
Scyphomedusae. These ectodermal pits were all originally respiratory
organs. "The essence of all these propositions," he writes, "lies in the
fact that the segmented animals are traced back not to a triploblastic
unsegmented ancestor, but to a two-layered Coelenterate-like animal with
a pouched gut, the pouching having arisen as a result of the necessity
for an increase in the extent of the vegetative surfaces in a rapidly
enlarging animal (for circulation and respiration)" (p. 47). "I have
attempted to show," he writes further on, "that the majority of the
Triploblastica ... are built upon a common plan, and that that plan is
revealed by a careful examination of the anatomy of Coelenterata; that
all the most important organ-systems of these Triploblastica are found
in a rudimentary condition in the Coelenterata; and that all the
Triploblastica referred to must be traced back to a diploblastic
ancestor common to them and the Coelenterata" (p. 68). The main
assumption was that the neural or blastoporal surface must be homologous
throughout the Metazoa, though it was dorsal in the Chordata, ventral in
the Annelida and Arthropoda. He derived the central nervous system of
the Chordata from the circumoral ring of the common ancestor by means of
the hypothesis that both the pre-blastoporal and the post-blastoporal
parts of it disappeared.[451]

The characteristic relation of the central nervous system to the
blastopore in Annelida and Vertebrates had already been pointed out by
Kowalevsky,[452] who had also sketched a theory of the common descent of
these two phyla from an ancestral form in which the nervous system
encircled the blastopore.

In 1882, before the publication of Sedgwick's papers, A. Lang[453] had put
forward the somewhat similar view that the stomach-diverticula of the
Turbellaria, which he had found to be segmentally arranged in certain
Triclads, were the morphological equivalents of the enterocoelic pouches
of higher animals. This view, however, he soon gave up.[454] Sedgwick's
views found a supporter in A. A. W. Hubrecht,[455] who utilised them in
connection both with his speculations on the relation of Nemertines to
Vertebrates, and with his exhaustive work on the early development of
the Mammalia. He postulated as the far-back ancestor of Vertebrates, "an
actinia-like, vermiform being, elongated in the direction of the
mouth-slit" (p. 410, 1906), and derived the central nervous system from
the circum-oral ring of this primitive form, the notochord from its
stomodaeum, and the coelom from the peripheral parts of the gastric
cavity (p. 169, 1909).

[424] Gegenbaur, _Zeits. f. wiss. Zool._, v., 1853.

[425] Remak, _loc. cit._, p. 183, pl. xii.

[426] Lereboullet, _Ann. Sci. nat._ (4) xviii., pp. 118-9,
1862.

[527] Lereboullet, in Remak, p. 183 f.n.

[428] Kowalevsky, _Mem. Acad. Sci. St
Petersbourg_ (Petrograd), (7), x. and xi., 1866 and 1867.

[429] A. Agassiz, _Contrib. Nat. Hist. United States_, v.,
1864.

[430] _Mem. Acad. Sci. St Petersbourg_ (Petrograd), (7),
xiv., 1869.

[431] "Embryolog. Studien an Wuermern u. Arthropoden,"
_Mem. Acad. Sci. St Petersbourg_ (Petrograd), (7), xvi.,
1870.

[432] _Die Kalkschwaemme_, 3 vols., Berlin, 1872. General
chapters translated in _Ann. Mag. Nat. Hist._ (4), xi.,
pp. 241-62, 421-30, 1873.

[433] "Die Gastraea-Theorie, die phylogenetische
Classification des Thierreichs und die Homologie der
Keimblaetter." _Jenaische Zeitschrift_, viii., pp. 1-55,
1874. "Die Gastrula und die Eifurchung der Thiere,"
_ibid._, ix., pp. 402-508, 1875. "Die Physemarien,
Gastraeaden der Gegenwart," and "Nachtraege zur
Gastraea-Theorie," _ibid._, x., pp. 55-98, 1876.
Republished in _Biologische Studien_, 2nd part, _Studien
zur Gastraea-Theorie_, 270 pp., 14 pls., Jena, 1877.

[434] See _Ann. Mag. Nat. Hist._ (4), xi., p. 253.

[435] Term first introduced in _Die Kalkschwaemme_, p. 468,
1872.

[436] "On the Primitive Cell-layers of the Embryo as the
Basis of Genealogical Classification of Animals, and on
the Origin of Vascular and Lymph Systems," _Ann. Mag.
Nat. Hist._ (4), xi., pp. 321-38, 1873.

[437] First distinguished in _Die Kalkschwaemme_, i., p.
465.

[438] Even in the 'seventies it was still believed by many
that the egg-nucleus disappeared on fertilisation. The
true nature of the process was not fully made out till
1875, when O. Hertwig observed the fusion of egg- and
sperm-nuclei in _Toxopneustes (Morph. Jahrb._, i.,
1876).

[439] _Studien z. Gastraea-Theorie_, p. 214, 1877. These
forms were known even in 1870 (Carter, _Ann. Mag. Nat.
Hist._ (4), vi., pp. 346-7), to be Foraminifera. The
figures of supposed collar-cells, etc., do credit to
Haeckel's imagination.

[440] _History of Creation_, Eng. Trans., ii., pp. 278 ff.

[441] _Systematische Phylogenie_, iii., p. 41, Berlin,
1895.

[442] "Notes on the Embryology and Classification of the
Animal Kingdom," _Q.J.M.S._ (n.s.), xvii., pp. 399-454,
1877.

[443] It was "part of the non-historic mechanism of
growth" (_loc. cit._, p. 418).

[444] _Treatise on Comparative Embryology_, ii., chap.
xiii., 1881. For a modern discussion of this problem,
see Hubrecht, _Q.J.M.S._, xlix., 1906.

[445] See Balfour, _loc. cit._, Chapter xiii.

[446] _A Treatise on Zoology_, Pt. ii., 1900. Introduction
by Sir E. Ray Lankester.

[447] _Studien zur Blaettertheorie_, Jena, 1879-80. "Die
Coelomtheorie, Versuch einer Erklaerung des mittleren
Keimblattes," _Jenaische Zeitschrift_, xv., pp. 1-150,
1882.

[448] For an historical account of this work, see
Lankester, _loc. cit._, pp. 21-37.

[449] _Proc. Roy. Soc._, 1883, and _Q.J.M.S._, xxiii.,
1883.

[450] "Origin of Metameric Segmentation," _Q.J.M.S._,
xxiv., pp. 43-82 1884.

[451] See further the same author's article "Embryology"
in the _Ency. Brit._, vol. xi., 11th ed., Cambridge,
1910.

[452] _Arch. f. mikr. Anat._, xiii., pp. 181-204, 1877.

[453] "Der Bau von Gunda segmentata," _Mitth. Zool. Stat.
Neap._, iii., pp. 187-250, 1882.

[454] "Die Polycladen," _Fauna u. Flora des Golfes von
Neapel_, Monog. v., Leipzig, 1884, and "Beitraege zu
einer Trophocoeltheorie," _Jen. Zeits._, xxxviii., pp.
1-373, 1904 (which see for a modern account of theories
of metamerism).

[455] "Die Abstammung der Anneliden u. Chordaten," _ Jen.
Zeits._, xxxix., pp. 151-76, 1905. "The Gastrulation of
the Vertebrates," _Q.J.M.S._, xlix., pp. 403-19, 1906.
"Early Ontogenetic Phenomena in Mammals," _Q.J.M.S._,
liii., pp. 1-181, 1909.




CHAPTER XVII

THE ORGANISM AS AN HISTORICAL BEING


"Of late the attempt to arrange genealogical trees involving
hypothetical groups has come to be the subject of some ridicule, perhaps
deserved. But since this is what modern morphological criticism in great
measure aims at doing, it cannot be altogether profitless to follow this
method to its logical conclusions. That the results of such criticism
must be highly speculative, and often liable to grave error, is
evident."

The quotation is from Bateson's paper of 1886, and it is symptomatic of
the change which was soon to come over morphological thought. New
interests, new lines of work, began to usurp the place which pure
morphology had held so long.

This is accordingly a convenient stage at which to take stock of what
has gone before, to consider the relation of evolutionary morphology to
the transcendental and the Cuvierian schools of thought which preceded
it, and to make clear what new element evolution-theory added to
morphology.

The close analogy between evolutionary and transcendental morphology has
already been remarked upon and illustrated in the last three chapters.
We have seen that the coming of evolution made comparatively little
difference to pure morphology, that no new criteria of homology were
introduced, and that so far as pure morphology was concerned, evolution
might still have been conceived as an ideal process precisely as it was
by the transcendentalists. The principle of connections still remained
the guiding thread of morphological work; the search for archetypes,
whether anatomical or embryological, still continued in the same way as
before, and it was a point of subordinate importance that, under the
influence of the evolution-theory, these were considered to represent
real ancestral forms rather than purely abstract figments of the
intelligence. The law of Meckel-Serres was revived in an altered shape
as the law of the recapitulation of phylogeny by ontogeny; the natural
system of classification was passively inherited, and, by a _petitio
principii_, taken to represent the true course of evolution. It is true
that the attempt was made to substitute for the concept of homology the
purely genetic concept of homogeny, but no inkling was given of any
possible method of recognising homogeny other than the well-worn methods
generally employed in the search after homologies.

There was a close spiritual affinity between the speculative
evolutionists and the transcendentalists. Both showed the same
subconscious craving for simplicist conceptions--the transcendentalists
clung fast to the notion of the absolute unity of type, of the ideal
existence of the "one animal," and the evolutionists did precisely the
same thing when they blindly and instinctively accepted the doctrine of
the monophyletic descent of all animals from one primeval form. Geoffroy
persisted in regarding Arthropods as being built on the same plan as
Vertebrates: Dohrn and Semper did nothing different when they derived
both groups from an ancestor combining the main characters of both. The
determination to link together all the main phyla of the animal kingdom
and to force them all into a single mould was common to evolutionary and
pre-evolutionary transcendentalists alike.

From the fact that all Metazoa develop from an ovum which is a simple
cell, the evolutionists inferred that all must have arisen from one
primordial cell. From the fact that the next step in development is the
segmentation of the ovum, they argued that the ancestral Metazoa came
into being through the division of the primal Protozoon with aggregation
of the division-products. From the fact that a gastrula stage is very
commonly formed when segmentation has been completed, they assumed that
all germ-layered animals were descended from an ancestral Gastraea.

They quite ignored the possibility that a different explanation of the
facts might be given; they seized upon the simplest and most obvious
solution because it satisfied their overwhelming desire for
simplification. But is the simplest explanation always the
truest--especially when dealing with living things? One may be permitted
to doubt it. It is easy to account for the structural resemblance of the
members of a classificatory group, by the assumption that they are all
descended from a common ancestral form; it is easy to postulate any
number of hypothetical generalised types; but in the absence of positive
evidence, such simplicist explanations must always remain doubtful. The
evolutionists, however, had no such scruples.

Phylogenetic method differed in no way from transcendental--except
perhaps that it had learnt from von Baer and from Darwin to give more
weight to embryology. The criticisms passed by Cuvier and von Baer upon
the transcendentalists and their recapitulation theory might with equal
justice be applied to the phylogenetic speculations which were based on
the biogenetic law. There was the same tendency to fix upon isolated
points of resemblance and disregard the rest of the organisation. Thus,
on the ground of a presumed analogy of certain structures to the
vertebrate notochord, several invertebrate groups, as the Enteropneusta,
the Rhabdopleura, the Nemertea, were supposed to be, if not ancestral,
at least offshoots from the direct line of vertebrate descent. And if
other points of resemblance could in some of these cases be discovered,
yet no successful attempt was made to show that the total organisation
of any of these forms corresponded with that of the Vertebrate type.
With the possible exception of the Ascidian theory, all the numerous
theories of vertebrate descent suffered from this irremediable defect,
and none carried complete conviction.

In spite of the efforts of the evolutionists, as of those of the
transcendentalists, the phyla or "types" remained distinct, or at best
connected by the most general of bonds.

The close affinity of transcendentalists and evolutionists is shown very
clearly in their common contrast in habits of thought with the Cuvierian
school. It is the cardinal principle of pure morphology that function
must be excluded from consideration. This is a necessary and unavoidable
simplification which must be carried out if there is to be a science of
pure form at all. But this limitation of outlook, if carried over from
morphology to general biology becomes harmful, since it wilfully ignores
one whole side of life--and that the most important. The functional
point of view is clearly indispensable for any general understanding of
living things, and this is where the Cuvierian school has the advantage
over the transcendental--its principles are applicable to biology in
general.

Geoffroy and Cuvier in pre-evolutionary times well typified the contrast
between the formal and the functional standpoints. For Geoffroy form
determined function, while for Cuvier function determined form. Geoffroy
held that Nature formed nothing new, but adapted existing "materials of
organisation" to meet new needs. Cuvier, on the other hand, was always
ready to admit Nature's power to form entirely new organs in response to
new functional requirements.

The evolutionists followed Geoffroy rather than Cuvier. They laid great
store by homological resemblances, and dismissed analogies of structure
as of little interest. They were singularly unwilling to admit the
existence of convergence or of parallel evolution, and they held very
firmly the distinctively Geoffroyan view that Nature is so limited by
the unity of composition that she can and does form no new organs.

By no one has this underlying principle of evolutionary morphology been
more explicitly recognised than by Hubrecht, who in his paper of 1887,
after summarising the points of resemblance between Nemertines and
Vertebrates which led him to assume a genetic connection between them,
writes as follows:--"At the base of all the speculations contained in
this chapter lies the conviction, so strongly insisted upon by Darwin,
that new combinations or organs do not appear by the action of natural
selection unless others have preceded, from which they are gradually
derived by a slow change and differentiation.

"That a notochord should develop out of the archenteric wall because a
supporting axis would be beneficial to the animal may be a teleological
assumption, but it is at the same time an evolutional heresy. It would
never be fruitful to try to connect the different variations offered,
_e.g._, by the nervous system throughout the animal kingdom, if similar
assumptions were admitted, for there would be then quite as much to say
for a repeated and independent origin of central nervous systems out of
indifferent epiblast just as required in each special case. These would
be steps that might bring us back a good way towards the doctrine of
independent creations. The remembrance of Darwin's, Huxley's, and
Gegenbaur's classical foundations, and of Balfour's and Weismann's
brilliant superstructures, ought to warn us away from these dangerous
regions" (p. 644).

This same prejudice lies at the root of the idea of _Functionswechsel_,
in spite of the general functional orientation of that idea.

Dohrn's constant assumption is that Nature makes shift with old organs
wherever possible, instead of forming new ones. He derives gill-slits
from segmental organs, fins and limbs from gills, ribs from gill-arches,
and so on, instead of admitting that these organs might quite as well
have arisen independently. He objects on principle to the origin of
organs _de novo_. Thus, rebutting the suggestion that certain organs
which are not found in the lower Vertebrates might have arisen as new
formations, he writes:--"Against this supposition the whole weight of
all those objections can be directed that are to be brought in general
against the method of explanation which consists in appealing without
imperative necessity to the _Deus ex machina_, 'New formation,' which is
neither better nor worse than _Generatio equivoca_" (p. 21).

Of a similar nature was the objection to convergence.[456]

Why, we may ask, were morphologists so unwilling to admit the creative
power of life? Dohrn, for instance, was fully aware of the great
transforming influence exerted by function upon form--his theory of
_Functionswechsel_ regards as the most powerful agent of change the
activity of the animal, its effort to make the best use of its organs,
to apply them at need in new ways to meet new demands. Why then did he
not go a step further and admit that the animal could by its own
subconscious efforts form entirely new organs? Why did most
morphologists join with him in belittling the organism's power of
self-transformation?

The reasons seem to have been several. There is first the fundamental
reason, that the idea of an active creative organism is repugnant to the
intelligence, and that we try by all means in our power to substitute
for this some other conception. In so doing we instinctively fasten upon
the relatively less living side of organisms--their routine habits and
reflexes, their routine structure--and ignore the essential activity
which they manifest both in behaviour and in form-change.

We tend also to lay the causes of form-change, of evolution, as far as
possible outside the living organism. With Darwin we seek the
transforming factors in the environment rather than within the organism
itself. We fight shy of the Lamarckian conception that the living thing
obscurely works out its own salvation by blind and instinctive effort.
We like to think of organisms as machines, as passive inventions[457]
gradually perfected from generation to generation by some external
agency, by environment or by natural selection, or what you will. All
this makes us chary of believing that Nature is prodigal of new organs.

Other causes of the unwillingness of morphologists to admit the new
formation of organs are to be sought in the main principle of pure
morphology itself, that the unity of plan imposes an iron limit upon
adaptation, and in the powerful influence exercised at the time by
materialistic habits of thought. Teleology had become a bugbear to the
vast majority of biologists, and all real understanding of the Cuvierian
attitude seems, in most cases, to have been lost, although, curiously
enough, teleological conceptions were often unconsciously introduced in
the course of discussions on the "utility" of organs in the struggle for
existence.

Evolutionary morphology, being for the most part a form of pure or
non-functional morphology, agreed then in all essential respects with
pre-evolutionary or transcendental morphology.

But it contained the germ of a new conception which threw a new light
upon the whole science of morphology. This was the conception of the
organism as an historical being.

We have seen this thought expressed with the utmost clearness by Darwin
himself (_supra_, p. 233). In his eyes the structure and activities of
the living thing were a heritage from a remote past, the organism was a
living record of the achievements of its whole ancestral line. What a
light this conception threw upon all biology! "When we no longer look at
an organic being as a savage looks at a ship as something wholly beyond
his comprehension; when we regard every production of Nature as one
which has had a long history; when we contemplate every complex
structure and instinct as the summing-up of many contrivances, each
useful to the possessor, in the same way as any great mechanical
invention is the summing-up of the labour, the experience, the reason,
and even the blunders of numerous workmen; when we thus view each
organic being, how far more interesting--I speak from experience--does
the study of natural history become!" (_Origin_, 6th ed., pp. 665-6).

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