658 
p. 213). The same subject has now heen further in- 
vestigated by Mr. D. Lloyd-Jones (Journ. Experi- 
mental Zoology, vol. xviii., No. 3) in a microscopical 
and chemical study of the feather-pigments. Red 
colour is due to red-brown pigment-granules which 
are present in the intermediate cells of the epidermis 
as well as in special pigment-cells. This pigment, if 
very finely divided, produces yellow. Black pigment 
under various conditions produces black, dun, blue, 
or silver. 
Pigeons serve also as the subject of an inquiry into 
“Sex Ratios’’ by Drs. L. J. Cole and W. F. Kirk- 
patrick (Rhode Island Agric. Exp. Station, Bulletin 
162). The normal ratio calculated from a large num- 
ber of broods is 105 males to 100 females, and the 
death-rate is especially high for the first three days 
after hatching and at the age of about a fortnight. 
It is well known that the pigeon’s normal brood con- 
sists of two eggs. In the recorded cases there were 
284 bisexual broods to 302 unisexual; of the latter 
149 consisted of two males and 153 of two females— 
a result indicating almost perfect equality. The death- 
rate of males and females in the bisexual broods is 
essentially equal. ‘‘A comparison of the numbers of 
each sex hatched from first and from second eggs 
respectively shows no tendency for the former to pro- 
duce exclusively males and the latter females, but more 
males than females are hatched from both.” The 
authors conclude that ‘‘sex in pigeons is determined 
according to the laws of chance’’—in Mendelian ter- 
minology the individuals of one sex are heterozygous, 
and those of the other homozygous as regards the sex- 
determining factors. Gere Ce 
BIOMETRICS AND MAN. 
jy part iv. of vol. x. of Biometrika, Mr. H. Waite 
publishes an interesting study, based on two 
thousand complete sets of finger-prints of adult males, 
part of a series in the biometric laboratory, University 
College, London. It appears that the various types of 
finger-print are not scattered at random over the 
fingers; certain types are more or less peculiar to 
certain fingers, and the appearance of one type is 
associated with that of another. In this respect cer- 
tain fingers are more closely related to each other 
than to any third finger, and the distribution of this 
relationship is in general similar to that of the corre- 
lations of the bones of the same fingers. In the same 
number, Dr. Alice Lee discusses the influence of 
segregation on tuberculosis, a question to which much 
attention has been devoted of recent years. No method 
of measuring the extent of segregation is, however, 
found satisfactory, and the various methods used, for 
example, by Dr. Newsholme, lead, when examined by 
more stringent methods, to contradictory and incon- 
clusive results. Whether there is any really substan- 
tial relation between the prevalence of phthisis and 
institutional segregation may remain an open ques- 
tion, but Dr. Lee is of opinion that no such relation 
has been demonstrated. Miss Elderton and Prof. 
Pearson similarly fail to find any evidence that isola- 
tion reduces the attack-rate from diphtheria; no ap- 
preciable influence on the attack-rate is found in cer- 
tain data placed at their disposal by the medical officer 
of health for Coventry, though the death-rate may be 
lowered. 
In the same journal Prof. Pearson, in collaboration 
with Miss Elderton, contributes an important memoir 
on further evidence of natural selection in man. The 
variate-difference correlation method is applied to the 
death-rates for males and for females in England and 
Wales from 1850 to 1908. The correlation between 
death-rates for successive years of life, over a long 
NO. 2389, VOL. 95] 

NATURE 


[AUGUST 12, 1915 

series of years, is high and positive. But the correla- 
tion of first differences is negative, and this negative 
correlation increases in intensity as higher and higher 
differences are taken, until fairly steady values are 
reached for the sixth differences, ranging round —o-7. 
Thus for males the correlation of sixth differences in 
the first and second years of life is —o-688, in the 
fourth and fifth years of life —o-695. For females the 
corresponding figures are —o-71g9 and —o-736. The 
correlations in each case are taken between death-rates 
of those born in the same year. At an interval of two 
years the partial correlations are negative but much 
lower; at three and four years’ interval the signs are 
irregular and the results inconclusive. To assert the 
existence of selection and measure its intensity, the 
authors remind their readers, must be distinguished 
from advocacy of a high infantile mortality as a factor 
of racial efficiency. 
We can only briefly direct attention to two articles 
by Mr. R. A. Fisher on the frequency distribution of 
the correlation coefficient in samples from an in- 
definitely large population, and on the distribution of 
standard derivations of small samples. 

REPORTS ON MINING INDUSTRIES. 
WO reports issued by the Canadian Department 
of Mines (‘‘Peat, Lignite, and Coal,” by B. F. 
Haanel; ‘‘ Report on the Non-Metallic Minerals Used 
in the Canadian Manufacturing Industries,” by 
Howells Frechette; Ottawa, 1914) are further examples 
of the sedulous care witht which the Canadian Govern- 
ment is endeavouring to foster the industry of mining 
in the Dominion. ‘The report upon peat, lignite, and 
coal deals exclusively with the application of these 
fuels to the generation of power-gas and to the 
recovery of by-products, the latter being chiefly 
ammoniacal salts. An elaborate study has been made 
of the various methods of dealing with peat in Europe, 
although, for some reason not easy to understand, 
Russian practice appears not to have been included, 
in spite of the fact that conditions in Russia resemble 
more closely these in Canada than do any of the 
other countries investigated. The first part of the 
report is taken up with a discussion of the various 
methods of producing peat fuel; it is interesting to 
note that the author has devoted a good deal of atten- 
tion to the well-known Ekenherg process of wet 
carbonisation, and that his conclusions are decidedly 
unfavourable to the process. He points out that the 
most recent report on the subject by Lassen shows 
“that in continuous operation on a large scale, a 
moisture content below 7o per cent. in the pressed 
cake cannot be counted on,”’ and dismisses the subject 
with the following statement :— 
“Although large funds have been placed at the 
disposal of various investigators in order to enable 
them to demonstrate the economic value of the pro- 
cess, and although a private company has conducted 
elaborate experiments on a large scale, involving the 
expenditure of a large amount of money, not one ton 
of peat fuel has been manufactured on a commercial 
scale by means of this process.” 
The author’s opinion of the Brune and Horst 
process for pressing out the water is equally 
unfavourable, nor is he greatly impressed by 
the possibilities of any of the methods of arti- 
ficial drying, and sums up in favour of air-dried 
peat. He shows that under normal Canadian condi- 
tions peat can be utilised to advantage for the pro- 
duction of gas provided that it contains not more than 
40 per cent. of moisture and that it can be obtained 
at a cost not exceeding 1.50 dollars (6s. 3d.) per ton 
of peat containing 30 per cent. of moisture. He holds 

