N, their children N(A) in the first case will be all normal
in appearance but will be carrying albinism recessive; and
in the second case some will be pure normal individuals
N, and some will be like the children of the first brother,
i.e. N(A). Now, if one of these latter children of the
second brother marries a cousin---a child of the first
brother,---their offspring, if large enough, will consist of
some pure normals N, impure normals N(A), and of albinoes A.
Ab X N (A)Nb X N
| |
N(A) N(A)+N
|
N+2N(A)+A
No other rational explanation of the close relationship
between albinism and cousin marriages is at present
forthcoming. And, when the whole facts are borne in
mind, there can be no reasonable doubt that the Mendelian
principles offer an intelligible solution of the problem.
A popular conception exists that albinoes are less
constitutionally strong than the pigmented individuals of
the same species. In support of this belief there is more or
less scientifically ascertained evidence. Conversely, there
is, however, conclusive evidence that in some instances and
in respect of certain qeialities the opposite belief is true.
To deal with the former belief first, we have the remarkable
case cited by Charles Darwin on the authority of Professor I. J.
Wyman. In Virginia the paint-root plant (Lachnanthes
tinctoria) occurs abundantly, and Professor Wyman noticed
that all the pigs in this district were black. Upon inquiry
of the farmers he found that all the white pigs born in a
litter were destroyed, because they could not be reared to
maturity. The root of this plant, when eaten by white pigs,
caused their bones to turn to a pink colour and their hoofs
to fall off, but the black pigs could eat the same plant with
impunity. Partial albinism in this case was undoubtedly
correlated with some inherent constitutional defect, in
virtue of which the individuals characterized by it were
injuriously affected by the juices of a plant quite innocuous
to their pigmented brethren. Heusinger has shown that
white sheep and pigs are injured by the ingestion of certain
plants, while the pigmented individuals may eat them without
harm. In Devonshire and in parts of Kent the farmers entertain
a marked prejudice against white pigs, because ``the sun
blisters their skin.'' More remarkable is the case of certain
cattle, whose skin is piebald, marked by a general ground
colour over which are scattered patches of unpigmented coat.
In these animals, in certain inflammatory skin eruptions,
caused by the ingestion of harmful plants, the albinotic
areas are alone affected. And with certain cutaneous diseases
accompanied by constitutional disturbances which afflict
cattle, the affection in the skin appears on the patches
bearing white hairs, the other parts remaining apparently
healthy. Such cases suggest that we should be more correct
in regarding, not albinism as correlated with constitutional
defects, but rather pigmentation as correlated with powers
of immunity or increased resistance against certain injurious
processes. In the West Indies ``the only horned cattle
fit for work are those which have a good deal of black in
them; the white are terribly tormented by the insects and
they are weak and sluggish in proportion to the black.''
Coming to man, it is known that some albino negroes are peculiarly
sensitive to the bites of insects; and with Europeans it is a
generally observed fact that the fairer individuals are more
seriously affected by the bites of fleas and bugs than are darker
ones. Dr Twining, in the British Association Reports for
1845, p. 79, cites some instances described by Humboldt, who
says that the copper-coloured natives of the high plain of
Bogoto, and at a lower level on the Magdalena river, were
generally free from goitre. Professor Poffig, also cited
by Dr Twining, states that on the east side of the Andes in
Chile, in some of the races which live there, he did not see
a single case of goitre, and yet in the white inhabitants, who
live exactly as the natives, it prevails in a great degree:
Turning now to instances of the opposite kind, it is known
that silkworms which spin colourless cocoons are more resistant
to the attacks of a certain deadly fungus than are those
which spin the yellow ones. In some parts of North America
it is found that the white peaches are much less liable to
the attack of a disease known as the ``yellows'' than are
the yellow-fleshed ones. In the region of the Mississippi,
Farabee has observed that the albino negroes are taller and
broader than the black-skinned individuals. We may assume
that increased stature and breadth imply some sort of inherent
physical superiority, and if such an assumption is valid we
have in man evidence that albinism is correlated not with
constitutional defectiveness but with greater perfectness.
But the question as to whether albinoes are more or less
constitutionally vigorous than pigmented individuals of the
same species may be tested by exact measurement. In 1893 W. D.
Halliburton and T. G. Brodie, in ascertaining the physiological
pijoperties of nucleo-proteids, found that when they were
intravascularly injected into pigmented rabbits, coagulation
of the blood resulted, but of the eight albinoes which they
used, none clotted. At a subsequent period (1897) Halliburton
and J. W. Pickering showed that the three synthesized colloids
of Grimaux in the same way produced coagulation in pigmented
animals, but failed to do so in albinoes. Pickering, still
later, showed, in the case of four Norway hares, two of
which were injected while in their pigmented or summer
coat, and two while in their albino or winter coat, that
coagulation occurred in the former cases but not in the latter.
Quite recently, however, the author of this article has made
a more detailed examination of the question, operating upon
several hundreds of rabbits. And he found that all albinoes
do not fail to clot when intravascularly injected with
nucleoproteids. Only about 9% of them thus failed absolutely
to manifest any trace of coagulation. But about 7% showed
an exceedingly limited coagulation, in which the clot was
colourless and flocculent, and confined to the heart. The
rest gave a typical and more or less wide-spread coagulation.
Moreover, it was found that all the failures of coagulation
occurred when the nucleo-proteid used was obtained from pigmented
animals. When it was derived from albinoes no failures
occurred. All pigmented animals clotted when the nucleo-proteid
was derived from either source. The Himalayan rabbits reacted
like complete albinoes, and 12% of them failed to clot when
injected with nucleo-proteid extracted from pigmented animals.
The interesting fact was thus ascertained that all albinoes are not
alike. To students of heredity this is precisely what would
have been expected. For, as the facts above described show,
albinoes, though apparently identical externally, are yet the
carriers of different hereditary characters. Among albino
rats, for instance, the author of this article has reason to
believe, upon theoretical grounds resting on an experimental
basis, that probably no less than thirteen types exist.
With rabbits and mice there must be a still larger number.
In the intravascular coagulation experiments above described,
all the rabbits were carefully weighed, and the amount of
nucleoproteid injected until coagulation occurred was measured.
This would give for albinoes and pigmented individuals the
amount per kilogramme of body-weight required to kill in each
case, and would afford a measurement of the relative resistance
of the two races. It was found that the resistance of albinoes
towards the coagulative effects of injected nucleo-proteids
was to that of pigmented individuals as 1.5 to 1.0. In this
case, the greater constitutional vigour of the albino is
thus accurately demonstrated. But it does not necessarily
follow that with other materials and with other constitutional
qualities the state of things would not be reversed.
One other feature remains to be mentioned. Albinism appears,
in the processes of heredity, to be sometimes indissolubly
correlated with certain peculiar traits. It is well known
that the long-haired albino rabbit, called Angora, when at
rest, has the habit of swaying its head sideways in a peculiar
fashion. C. C. Hurst has shown that the long-haired and
albino characters are always accompanied in heredity with the
swaying habit. The Angora character never occurs without it.
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ALBINONI, TOMASSO (c. 1674--c. 1745), Italian musician,
was born at Venice. He was a prolific composer of operas
attracting contemporary attention for their originality,
but is more remarkable as a composer of instrumental music,
which greatly attracted the attention of Bach, who wrote
at least two fugues on Albinoni's themes and constantly
used his basses for harmony exercises for his pupils.
ALBINOVANUS PEDO, Roman poet, flourished during the Augustan
