In the department of Biology which forms the subject of this essay,
the adaptation of means to an end is probably more evident than in
any other; and it is therefore of interest to compare, in a brief
introductory section, the older with the newer teleological views.
The distinctive feature of Natural Selection as contrasted with other
attempts to explain the process of Evolution is the part played by the
struggle for existence. All naturalists in all ages must have known
something of the operations of "Nature red in tooth and claw"; but it
was left for this great theory to suggest that vast extermination is
a necessary condition of progress, and even of maintaining the ground
already gained.
Realising that fitness is the outcome of this fierce struggle, thus
turned to account for the first time, we are sometimes led to associate
the recognition of adaptation itself too exclusively with Natural
Selection. Adaptation had been studied with the warmest enthusiasm
nearly forty years before this great theory was given to the scientific
world, and it is difficult now to realise the impetus which the works
of Paley gave to the study of Natural History. That they did inspire the
naturalists of the early part of the last century is clearly shown in
the following passages.
In the year 1824 the Ashmolean Museum at Oxford was intrusted to the
care of J.S. Duncan of New College. He was succeeded in this office by
his brother, P.B. Duncan, of the same College, author of a History of
the Museum, which shows very clearly the influence of Paley upon the
study of nature, and the dominant position given to his teachings:
"Happily at this time (1824) a taste for the study of natural history
had been excited in the University by Dr Paley's very interesting
work on Natural Theology, and the very popular lectures of Dr Kidd on
Comparative Anatomy, and Dr Buckland on Geology." In the arrangement of
the contents of the Museum the illustration of Paley's work was given
the foremost place by J.S. Duncan: "The first division proposes to
familiarize the eye to those relations of all natural objects which form
the basis of argument in Dr Paley's Natural Theology; to induce a mental
habit of associating the view of natural phenomena with the conviction
that they are the media of Divine manifestation; and by such association
to give proper dignity to every branch of natural science." (From
"History and Arrangement of the Ashmolean Museum" by P.B. Duncan: see
pages vi, vii of "A Catalogue of the Ashmolean Museum", Oxford, 1836.)
The great naturalist, W.J. Burchell, in his classical work shows the
same recognition of adaptation in nature at a still earlier date.
Upon the subject of collections he wrote ("Travels in the Interior of
Southern Africa", London, Vol. I. 1822, page 505. The references to
Burchell's observations in the present essay are adapted from
the author's article in "Report of the British and South African
Associations", 1905, Vol. III. pages 57-110.): "It must not be supposed
that these charms (the pleasures of Nature) are produced by the mere
discovery of new objects: it is the harmony with which they have been
adapted by the Creator to each other, and to the situations in which
they are found, which delights the observer in countries where Art has
not yet introduced her discords." The remainder of the passage is so
admirable that I venture to quote it: "To him who is satisfied with
amassing collections of curious objects, simply for the pleasure of
possessing them, such objects can afford, at best, but a childish
gratification, faint and fleeting; while he who extends his view beyond
the narrow field of nomenclature, beholds a boundless expanse, the
exploring of which is worthy of the philosopher, and of the best talents
of a reasonable being."
On September 14, 1811, Burchell was at Zand Valley (Vlei), or Sand Pool,
a few miles south-west of the site of Prieska, on the Orange River. Here
he found a Mesembryanthemum (M. turbiniforme, now M. truncatum) and also
a "Gryllus" (Acridian), closely resembling the pebbles with which their
locality was strewn. He says of both of these, "The intention of Nature,
in these instances, seems to have been the same as when she gave to the
Chameleon the power of accommodating its color, in a certain degree,
to that of the object nearest to it, in order to compensate for the
deficiency of its locomotive powers. By their form and colour, this
insect may pass unobserved by those birds, which otherwise would soon
extirpate a species so little able to elude its pursuers, and this juicy
little Mesembryanthemum may generally escape the notice of cattle and
wild animals." (Loc. cit. pages 310, 311. See Sir William Thiselton-Dyer
"Morphological Notes", XI.; "Protective Adaptations", I.; "Annals of
Botany", Vol. XX. page 124. In plates VII., VIII. and IX. accompanying
this article the author represents the species observed by Burchell,
together with others in which analogous adaptations exist. He writes:
"Burchell was clearly on the track on which Darwin reached the goal.
But the time had not come for emancipation from the old teleology. This,
however, in no respect detracts from the merit or value of his work.
For, as Huxley has pointed out ("Life and Letters of Thomas Henry
Huxley", London, 1900, I. page 457), the facts of the old teleology are
immediately transferable to Darwinism, which simply supplies them with a
natural in place of a supernatural explanation.") Burchell here seems
to miss, at least in part, the meaning of the relationship between the
quiescence of the Acridian and its cryptic colouring. Quiescence is an
essential element in the protective resemblance to a stone--probably
even more indispensable than the details of the form and colouring.
Although Burchell appears to overlook this point he fully recognised the
community between protection by concealment and more aggressive modes
of defence; for, in the passage of which a part is quoted above, he
specially refers to some earlier remarks on page 226 of his Vol. I. We
here find that even when the oxen were resting by the Juk rivier (Yoke
river), on July 19, 1811, Burchell observed "Geranium spinosum, with
a fleshy stem and large white flowers...; and a succulent species of
Pelargonium... so defended by the old panicles, grown to hard woody
thorns, that no cattle could browze upon it." He goes on to say, "In
this arid country, where every juicy vegetable would soon be eaten up by
the wild animals, the Great Creating Power, with all-provident wisdom,
has given to such plants either an acrid or poisonous juice, or sharp
thorns, to preserve the species from annihilation... " All these modes
of defence, especially adapted to a desert environment, have since
been generally recognised, and it is very interesting to place beside
Burchell's statement the following passage from a letter written by
Darwin, Aug. 7, 1868, to G.H. Lewes; "That Natural Selection would tend
to produce the most formidable thorns will be admitted by every one
who has observed the distribution in South America and Africa (vide
Livingstone) of thorn-bearing plants, for they always appear where the
bushes grow isolated and are exposed to the attacks of mammals. Even
in England it has been noticed that all spine-bearing and sting-bearing
plants are palatable to quadrupeds, when the thorns are crushed." ("More
Letters", I. page 308.)