150 
genetically (this term has been translated into the far 
less expressive ‘‘rectigrade”’) in one direction, and if 
there be no lagging behind, they all reach precisely 
the same end. This would be a case of transmuta- 
tion (true mutations in Waagen’s and Scott’s sense), 
producing new species without thereby increasing their 
number, whilst divergence always implies, at least 
potentially, increase of species, genera, families, &c. 
If for argument’s sake the mutations pass through 
the colours of the spectrum, and if each colour be 
deemed sufficient to designate a species, then, if all 
the tenth generations have changed from green to 
yellow and those of the twentieth generation from 
yellow to red, the final number of species would be 
the same. And even if some lagged behind, or re- 
mained stationary, these epistatic species (Eimer) are 
produced by a process which is not the same as that 
of divergence or variation in the usual sense. 
The two primary factors of evolution are environ- 
ment and heredity. Environment is absolutely insepar- 
able from any existing organism, which therefore must 
react (adaptation) and at least some of these results 
gain enough momentum to be carried into the next 
generation (heredity). 
The life of an organism, with all its experiments 
and doings, is its ontogeny, which may therefore be 
called the subject of evolution, but not a factor. 
Nor is selection a primary and necessary factor, since, 
being destructive, it invents nothing. It accounts, for 
instance, for the composition of the present fauna, but 
has not made its components. A subtle scholastic in- 
sinuation lurks in the plain statement that by ruthless 
elimination a black flock of pigeons can be produced, 
even that thereby the individuals have been made 
black. (But, of course, the breeder has thereby not 
invented the black pigment.) 
There can be no evolution, progress, without re- 
sponse to stimulus, be this environmental or constitu- 
tional, 7.e. depending upon the composition and the 
correlated working of the various parts within the 
organism. Natural selection has but to favour this 
plasticity, by cutting out the non-yielding material, 
and through inheritance the adaptive material will 
be brought to such a state of plasticity that it is 
ready to yield to the spur of the moment, and the 
foundation of the same new organs will thereby be 
laid, whenever the same necessity calls for them. 
Here is a dilemma. On one hand, the organism 
benefits from the ancestral experience; on the other, 
there applies to it de Rosa’s law of the reduction of 
variability, which narrows the chances of change into 
fewer directions. But in these few the changes will 
proceed all the quicker and farther. Thus progress 
is assured, even hypertely, which may be rendered 
by “‘over-doing a good thing.” 
Progress really proceeds by mutations, spoken of 
before, orthogenesis, and it would take place without 
selection and without necessarily benefiting the 
organism. It would be mere presumption that the 
seven-gilled shark is worse off than its six- or five- 
gilled relations; or to imagine that the newt with 
double trunk-veins suffers from this arrangement, 
which morphologically is undoubtedly inferior to the 
unpaired, azygous, &c., modifications. The fact that 
newts exist is proof that they are efficient in their 
way. Such orthogenetic changes are as predictable 
in their results as the river which tends to shorten its 
course to the direct line from its head waters to the 
sea. That is the rivers Entelechy and no. more due 
to purpose or design than is the series of improve- 
ments from the many gill-bearing partitions of a shark 
to the fewer, and more highly finished comb-shaped 
gills of a Teleostean fish. 
The success of adaptation, as measured by the 
NO. 2292, VOL. 92| 
NATURE 
[OcToBER 2, 1913 
morphological grade of perfection reached by an 
organ, seems to depend upon the phyletic age of the 
animal when it was first subjected to these “* tempta- 
tions.’’ The younger the group, the higher is likely 
to be the perfection of an organic system, organ, 
or detail. This is not a platitude. Vhe perfection 
attained does not depend merely upon the length of 
time available for the evolution of an organ. A recent 
Teleostean has had an infinitely longer time as a 
fish than a reptile, and this had a longer time than a 
mammal, and yet the same problem is solved in a 
neater, we might say in a more scientifically correct, 
way by a mammal than by a reptile, and the reptile 
in turn shows an advance in every detail in comparison 
with an amphibian, and so forth. 
A few examples will suffice :— 
The claws of reptiles and those of mammals; there 
are none in the amphibians, although some seem to 
want them badly, like the African frog Gampsos- 
teonyx, but its cat-like claws, instead of being horny 
sheaths, are made out of the sharpened phalangeal 
bones which perforate the skin. 
The simple contrivance of the rhinocerotic horn, 
introduced in Oligocene times, compared with the 
antlers of Miocene Cervicornia and these with the 
response made by the latest of Ruminants, the hollow- 
horned antelopes and cattle. The heel-joint; unless 
still generalised, it tends to become. intertarsal (at- 
tempted in some lizards, pronounced in some dino- 
saurs and in the birds) by fusion of the bones of the 
tarsus with those above and below, so that the tarsals 
act like epiphysial pads. Only in mammals epiphyses 
are universal. Tibia and fibula having their own, the 
pronounced joint is cruro-tarsal, and all the tarsals 
could be used for a very compact, yet non-rigid 
arrangement. The advantage of a cap, not merely 
the introduction of a separate pad, is well recognised 
in engineering. 
Why is it that mammalian material can produce 
what is denied to the lower classes? In other words, 
why are there still lower and middle classes? Why 
have they not all by this time reached the same grade 
of perfection? Why not indeed, unless because every 
new group is less hampered by tradition, much of 
which must be discarded with the new departure; and 
some of its energy is set free to follow up this new 
course, straight, with ever-growing results, until in 
its turn this becomes an old rut out of which a new 
iolt leads once more into fresh fields. 
SECTION E. 
GEOGRAPHY. 
Openinc Appress BY Pror. H. N. Dickson, 
PRESIDENT OF THE SECTION. 
Since the last meeting of this Section the tragic 
fate of Captain Scott’s party, after its successful 
journey to the South Pole, has become known; and 
our hopes of welcoming a_ great leader, after great 
achievement, have been disappointed. There is no 
need to repeat here the narrative of events, or to 
dwell upon the lessons afforded by the skill, and re- 
source, and heroic persistence, which endured to the 
end. All these have been, or will be, placed upon 
permanent record. But it is right that we should add 
our word of appreciation, and proffer our sympathy 
to those who have suffered loss. It is for us also to. 
take note that this last of the great Antarctic expedi- 
tions has not merely reached the Pole, as another has 
done, but has added, to an extent that few successful 
exploratory undertakings have ever been able to do, 
to the sum of scientific geographical knowledge. As 
the materials secured are worked out it will, I believe, 
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