JuNE 27, 1912] 
NATURE 
427 
dation are exposed to it, while only those with 
hereditary liability contract the disease in a severe 
form. 
We should expect that infection would be very 
active between husbands and wives, and between 
them greatest in the poorest class, where the 
chances of isolation are least. Yet in that class 
there is no correlation of disease in husband and 
wife, and in the professional class the correlation 
only rises to o'28—a value about equal to that 
for physical characters such as eye colour or 
stature, where it is clearly referable to selective 
mating. Thus between husbands and wives there 
is no clear evidence of infection at al. 
Between parents and children, on the other 
hand, there is clear proof of correlation, while 
the fact that a tuberculous mother is only very 
slightly more dangerous to the child than a tuber- 
culous father, and more dangerous only at very 
early stages of life, shows that the influence of 
infection, just appreciable in this case, is very 
small compared with that of heredity. 
A study of the death-rates from phthisis shows 
that, while a fall has been going on since returns 
were available, that fall was greatest between 
1866 and 1891, and has been less marked during 
the more recent years when the ways of the 
tubercle bacillus have been known, and the open 
‘air treatment become general. 
The facts, of which we have given but a few 
examples, point to a gradual elimination of sus- 
ceptible stocks by a process of racial selection 
as the chief cause of the diminished death-rate, 
and throw doubt on the efficacy of many of the 
remedies now confidently recommended. 
Prof. Pearson’s second lecture contains a power- 
ful plea for organised knowledge as a guide to 
social and legislative action. It gives many horri- 
fying if amusing examples of the mistakes which 
may follow a reliance on the recommendations 
of officials, politicians, or philanthropists, who 
bring to the consideration of social problems no 
knowledge of biology or modern _ statistical 
methods. 
THE GUETIVATION “OHMCOTTON.! 
HIS collection cf papers and reports on the 
subject of cotton, prepared for the most 
part by writers directly connected with the cul- 
tivation of this staple, and in every instance by 
authorities on the subject, provides a succinct 
review of the efforts which are being made in the 
various cotton-growing countries of the world to 
improve the quality of the product by careful 
selection of seed, sound methods of cultivation, 
and increased efficiency in the control of insect 
pests and diseases due to fungi. 
There are only two papers included in the col- 
lection. The first of these, by Mr. W. L. Balls, 
botanist to the Khedivial Agricultural Society, 
1 International Association of Tropical Agriculture and Colonial Develop- 
ment. ‘‘ Papers and Reports on Cotton Cultivation.” Presented to the 
International C ngress of Tropical Agriculture, Brussels, May, 1gro. 
Supplementary to the general ‘‘ Report on the Present Position of Cotton 
Cultivation.” By Dr. W. R. Dunstan. F.R.S. Pp. viti+320-+-map. 
(Paris: The Assrciation, 34 Rue Hamelin; British Section—London: 
Amperial Institute, S.W , rorr.) Price 5s. 
NO. 2226, voL. 89] 
Cairo, deals with the application of Mendelian 
principles in the breeding of cotton, and bears 
evidence of careful experiment and critical ob- 
servation. The second, by Mr. G. C. Dudgeon, 
at one time inspector of agriculture for British 
West Africa, is a painstaking attempt to sum- 
marise our knowledge of the identity and dis- 
tribution of the cottons in indigenous cultivation 
in the British West African colonies. These 
cottons the writer is able to deal with from per- 
sonal inspection and with a knowledge obtained 
at first hand; his paper thus forms a_ useful 
supplement to the well-known work on the wild 
and cultivated cotton-plants of the world which 
we owe to Sir G. Watt. 
From the reference point of view, however, the 
main value of the work resides in the series 
of reports dealing with the cultivation of 
cotton in the United States of America, including 
in this case also the Sandwich Islands and Porto 
Rico; in all the British colonies, dependencies, 
and protectorates; in the colonies of France, 
Germany, Portugal, Holland, and Belgium, and 
in a few foreign countries “from China to 
Peruse 
That the reports are not all of equal import- 
ance need scacely be said. Foremost in this 
respect, as in the position which it occupies in the 
collection, is the report supplied by the United 
States Department of Agriculture, the intrinsic 
value of which is enhanced by the _ pro- 
vision of an exhaustive list of the publications 
bearing on this subject which have ‘been issued 
by that active and well-organised department. 
The subject of cotton in India is exhaus- 
tively discussed by Mr. G. A. Gammie, cotton 
specialist to the Indian Agricultural Department. 
Important and full of interest is the corresponding 
report for the British West Indies forwarded by 
Dr. F. Watts, the Imperial Commissioner of Agri- 
culture. Interesting and valuable also are the 
reports by Dr. O. Warburg on cotton in the 
German colonies; by Mr. W. L. Balls on cotton 
in Egypt; and by Mr. H. P. Taveira on cotton 
in the Portuguese colonies. 
In alluding especially to these particular reports 
as perhaps the more important no reflection on 
the other reports which the volume includes is 
intended. As a matter of fact, the importance 
of a particular report depends rather on the area 
with which it deals than on the form in which 
it is presented. In this latter regard a high 
standard has been observed which reflects equal 
credit on the officers who have supplied the 
reports and on those responsible for editing them. 
If not all of equal importance, all the reports 
are of great value, and the volume in which they 
appear should prove a useful addition to the 
many standard works on the subject of cotton. 
One of the best features of the work is an 
excellent map of the cotton-growing areas of the 
world. With all its excellences, however, the 
work shows one lamentable defect: there is no 
good general index. The omission to provide 
this detracts considerably from the value of the 
collection as a ready work of reference. 
