Heredity of Hair-Form 
the curved ones are seen, in cross- 
section, to be flattened, being some- 
times only half as thick as broad. 
Going farther back, we find that 
the difference in appearance is due to 
a difference in the shape of the follicles 
from which the hairs grow: straight 
hair develops in a plain, cylindrical 
follicle, while the follicle which pro- 
duces the flattened types of hair is 
curved and inclined in relation to the 
skin. Apparently this change is one, 
the possibility of which is often present 
in human germ-plasm, for it breaks out 
occasionally when there is no heredi- 
tary history back of it, so far as can be 
discovered, for a number of generations. 
It was noticed very early in the 
Mendelian study of heredity that these 
types were inherited distinctly and 
segregated. Davenport pointed out! 
that the curved condition seemed to 
behave as a dominant and the straight 
condition as a recessive, although his 
figures show that this does not hold 
strictly true, so that it is probable we 
413 
are here dealing with a number of 
different heritable factors, instead of a 
single one—unless we suppose that it is 
a single factor which is subject to much 
variation. 
The accompanying photographs from 
David B. Mackie, of Manila, show two 
sisters at Pangasinan, Philippine Is- 
lands. They are the offspring of a 
Philippine woman who had the straight 
hair characteristic of the Malays, and 
an American negro with wooly hair. 
This father, however, in Mr. Mackie’s 
opinion, had some white blood, and 
therefore may be considered heterozy- 
gous for hair-form. Were this not the 
case, we should expect to find all his 
children with curling hair. The fact 
that one of the sisters has distinctly 
curling hair and the other distinctly 
straight hair is in itself fair evidence 
that the father was not a pure-blood 
negro. The photograph graphically 
illustrates the fact that hair-form is not 
a blending, but a segregating, character 
in heredity. 
Effects of Alcohol on Germ-Plasm 
That alcohol acts on the germ-plasm 
in such a way as to cause defects in 
offspring, has long been believed, but 
those who have investigated the evi- 
dence know that very little of it is valid. 
Dr. Raymond Pearl of the University 
of Maine is carrying on experiments 
with fowls to test the effect of alcohol, 
and finds no evidence that it has the 
effects attributed to it. A preliminary 
account of his experiments is given in 
tue Proc) Am: Philos. Soc:, - lV, ‘pp: 
243-259. He treated nineteen fowls 
with alcohol and raised 234 chicks from 
them. “Out of twelve different char- 
acters for which we have exact quantita- 
tive data, the offspring of treated 
parents, taken as a group, are superior 
to the offspring of untreated parents 
in eight characters” and inferior in two, 
while in the remaining two characters 
there is no distinguishable difference. 
The infant mortality, among chicks of 
treated parents, was decreased, the 
chicks were heavier than normal when 
hatched, and grew faster than the 
average. No deformities were found. 
Dr. Pearl thinks the effect of the treat- 
ment was to eliminate the weaker 
germs in the parents, so that only the 
stronger germs gave rise to offspring. 
He is continuing the experiment with 
larger numbers of birds to get data for 
several generations. 
1 Davenport, C. B., ‘“‘Heredity in Relation to Eugenics,” p. 34. New York, 1910. 
