718 
NATURE 
[FEBRUARY 26, 1914 
otherwise normally coloured, are inherited as 
typical Mendelian dominants, the affection being 
always transmitted in the direct line. On the 
other hand, many, probably the majority, of cases 
of complete or nearly complete albinism behave 
as recessives, and appear especially in the offspring 
of consanguineous marriages between affected 
stocks. 
When the more sharply defined cases have been 
separated out, there remains a large mass of 
material which still requires analysis, and one 
of the most hopeful ways of dealing with this 
seems to be by a comparison with cases in 
animals which have been or might be worked out 
experimentally. Such experiment has already 
shown, first, that skin and coat colour is due to 
the combined effect of at least two separately 
inherited factors, one of which is necessary for 
the production of any kind of pigment, while the 
other determines the colour of the pigment which 
is produced. Vertebrate albinos are commonly 
produced by the absence of the first factor, and 
may therefore bear the factors which determine 
particular colours, although they do not show 
them. Albinos are therefore not all alike in their 
inherited constitution, and it is probably only by 
disentangling the various factors involved that 
a complete understanding of the causes of human 
albinism will be obtained. Secondly, experiment 
with animals shows that piebalding is completely 
distinct from total albinism in its inheritance, and 
that if a piebald appears when an albino is crossed 
with a self-colour, this is not due to mosaic in- 
heritance, but to the fact that the albino bears 
the factor for piebalding—is, in fact, a piebald 
from which the pigment factor is lacking. 
Thirdly, there is evidence that some cases of lack 
of pigment are due to an inhibiting factor which 
interferes with the development of pigment, even 
in the presence of both the required colour-factors. 
When complications of this kind have been shown 
to exist in animals which can be subjected to 
rigorously controlled experiment, it is not sur- 
prising that the examination of human albinos 
and their pedigrees reveals irregularities. 
A comparison with animal cases suggests, how- 
ever, that by the careful collection of evidence, 
and especially by the classification of cases (1) 
according to the results of clinical observation, 
supplemented by microscopical examination when 
possible, and (2) according to the mode of inherit- 
ance, much could be done to disentangle the 
various factors which are involved. Much of the 
preliminary work in this direction could be done 
with the data now available, but as long as we 
continue to group together, in thought as well as 
in name, such different phenomena as total absence 
of pigment, general reduction of pigment, pie- 
balding, and wall-eye, and, from the point of view 
of inheritance, cases which are clear Mendelian 
dominants, others which. are. scarcely less clearly 
recessive, and others, again, which have un- 
doubted sex-limited inheritance, so long the present 
confusion. will continue. 
The monograph before us, though scarcely 
NO. 2313, VOL. 92| 
-Dr. John A. 
making any attempt at a classification such as we 
suggest, will provide most useful material for 
future workers on the subject. It gives a full 
account of the clinical and microscopic characters 
of various kinds of albinism in the widest sense of — 
the word, both in man and animals; discusses their 
occurrence and geographical distribution, and in- 
cludes, in part iv., nearly 700 fully described pedi- 
grees, some of them extending to 100 or more 
individuals. 
PROF. S. P. LANGLEY AND AVIATION. 
I have brought to a close the portion of the work 
which seemed to be specially mine, the demonstration 
of the practicability of mechanical flight; and for the ' 
next stage, which is the commercial and practical 
development of the idea, it is probable that the world 
may look to others. The world, indeed, will be 
supine if it do not realise that a new possibility has 
come to it, and that the great universal highway 
overhead is now soon to be opened. 
ge Bus spoke the late secretary of the Smith- 
; sonian Institution, Samuel Pierpont Lang- 
ley, after his memorable experiment of May 6, 
1896, in which he launched a_heavier-than-air 
machine in the air, which flew under its own 
power (steam), traversing a distance of half a 
mile. This experiment it was that convinced the 
world of the practicability of mechanical flight, 
and which crowned the success of all his previous” 
experimental researches. It was not until the 
year 1903 (December 17) that the Brothers 
Wright, Wilbur and Orville, fitted a motor to 
their gliding machine, and made two flights, the 
first successful flights ever made by man in a 
heavier-than-air machine driven by its own power. 
It was a fitting tribute of the Board of Regents — 
of the Smithsonian Institution to found, on 
December 15, 1908, a Langley medal “to be 
awarded for specially meritorious investigations 
in connection with the science of aerodromics and 
its application to aviation,” and it was most 
appropriate that the brothers Wilbur and Orville 
Wright were the first (1909) to receive the award. 
The presentation of this medal is now made on 
May 6, a date selected in order that the cere- 
monies incident to the presentation may take place 
in connection with the observance of “Langley 
Day,” which was established by the Aero Club of 
Washington in 1911 to commemorate Langley’s 
achievement. 
A recent Smithsonian Institution publication 
(No. 2233) contains an account of the exercises on 
the occasion of the presentation of the Langley 
Medal and the unveiling of the Langley Memorial 
Tablet on May 6, 1913, including the addresses 
of Dr. Alexander Graham Bell, Monsieur J. J. 
Jusserand, the Ambassador to the United States, 
Brashear, and the secretary, Dr. 
Charles D. Walcott. The bronze memorial tablet 
is situated in the Smithsonian building, and repre- 
sents Prof. Langley seated on a terrace where he 
has a clear view of the heavens, and, in a medi- 
tative mood, is observing the flight of birds, while 
in his mind he sees his aerodrome soaring above 
them. 
