NATURE 

SATURDAY, FEBRUARY 3, 1923. 

CONTENTS. 
PAGE 
The Science and Practice of Pure Milk Supply—II. 137 
Physics and Psychics. By Surgeon Rear Admiral 
rola Marsh Beadnell, R.N. . 139 
A Great American Agricultural Cyclopedia. By 
Sir E. J. Russell, F 140 
-aone A r! Electrical Scien ad AR. + 142 
rganic Chemistry. By i@ . . + 142 
Our Bookshelf % A F ° 143 
Letters to the Editor :— 
The Spectrum of Neutral Ielium.—Prof. om M. 
Hicks, F.R.S. 146 
Some Experiments on Rate ‘of Growth in a Polar 
Region (Spitsbergen) and in England. (///us- 
trated.)—Dr. J. H. Orton * 146 
Separation of Mercury into Isoto a in a Steel Appar- 
atus. (With diagrams.)— Prof. William D. 
Harkins and S. L. Madorsky 148 
The Rule of Priority in Nomenclature. sei, Chapman 148 
Selective Interruption of Molecular Oscillation. 
(With diagrams.)—Arthur Fairbourne. 149 
Sir Isaac Bayley Balfour. —Prof. T. D. A. Cockerell 1 50 
Age and Area in Natural Selection.—Dr. Hubert 
yman Clark . : 150 
The Cause of Anticyclones. Miss Catharine O. 
Stevens . js + 150 
The Name of the Pond Snail.—F. A. B. 150 
Medical Education.—Prof. W. J. Dakin . 151 
An Overlooked Feature in Four-legged Tadpoles of 
Rana temporaria. (With diagram )— ven H. 
Latter . Ps 
Smell and Specific Gravity Pe H. Kenneth" + 151 
Greek Geometry, with Special Reference to Infinit- 
esimals. By Sir T. L. Heath, ECB, F.RS. . 152 
The Disappearing Gap in the Spec: rum. (With dia- 
ae. -)—Il. By Prof. O. W. Richardson, F.R.S. 153 
Obituary : 
Prof. Johannes Orth . . ‘ ° 155 
Mr. E. W Nelson = - 150 
Dr. Talfourd El ‘ 156 
Current Topics and Ey ents « 156 
Our Astronomical Column S - P = + 159 
Research Items . 160 
The Lourengo Marques Meeting of the South African 
Association. By H. B. F. ° » 162 
Mental Character and Race . . . 164 
Scientific and Industrial Research . . F 165 
The Gold Coast Survey. (///ustrated) 166 
Paris Academy of Sciences’. 167 
University and Educational Intelligence ° 167 
Societies and Academies . . . 168 
Official Publications Eeereds “ . 172 
Diary of Societies . J 172 


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Editorial communications to the Editor. 
NO. 2779, VOL. 111] 

137 
The Science and Practice of Pure Milk 
Supply. 
Il. 
N last week’s article on this subject emphasis was 
placed on the importance of the consideration 
that efforts to secure pure milk satisfying scientific 
conditions should not, if possible, be permitted to 
reduce the total quantity of milk available for public 
use. There is little doubt that immediate action to en- 
force the supply of milk from non-tuberculous cattle 
would have this effect, and thus action beneficent in 
its intention would be inimical to the public welfare. 
There is every reason for excluding from milking 
herds all cows with diseased udders, or which can be 
shown to be giving milk containing tubercle bacilli. 
It is advisable to encourage farmers to clear their 
herds of tuberculosis, and to give special certificates 
to farmers who sell.milk only from cows proved free 
from tuberculosis by the tuberculin test. It may be 
desirable to go further than this for small herds of 
cattle, with a limited supply; for a single diseased 
cow in a small herd is much more dangerous to human 
consumers than when the bacillary milk is diluted 
in a vaster volume of milk. There are those who 
regard the imbibition of small quantities of tubercle 
bacilli in milk as a valuable means of securing partial 
human immunity ; but even if this be accepted as 
possible, the toleration implied by it of tuberculous 
infection of unknown dosage is unscientific, and the 
only sensible plan is to pasteurise milk from untested 
herds. Every human being receives tubercle bacilli 
of human origin in small doses, and the prevention 
of human tuberculosis may be said to consist—on the 
side of infection—in preventing too frequent or massive 
infection, beyond the powers of personal resistance. 
This is much more important for young children than 
for adults, whether the tuberculous infection is derived 
from milk or from a consumptive human patient, 
Pasteurisation then is a chief means of protection 
against the occasional dangers of milk. It is not an 
alternative to the hygiene of the cow and of the cow- 
shed, of transport, of sale, and of domestic storage. 
It is supplementary to them and aids their action. 
Nor can pasteurisation be said to encourage the 
continuance of a dirty milk supply. Milk which is 
dirty does not keep well after pasteurisation, and is 
thus unprofitable. The methods of 
pasteurisation improved, the flash method 
having been replaced by the “holder method ” of 
pasteurisation, which makes it more likely that the 
thilk will all be subjected to the temperature decided 
upon. Pasteurisation is still in process of improve- 
ment, as there is reason to think that in practice 
commercially 
have 
