AI2 
NATURE 
| FEsruary 28, 1907 
State Reports will be familiar with the style and most 
of the matter of this book, it is an undoubted advan- 
tage to have the information within reasonable 
compass. 
But Dr. Ries has not merely produced a condensed 
epitome of earlier publications; he has prepared a 
well-balanced, thoroughly practical work on American 
clays and clay-products, including a capital summary 
of our knowledge of the properties of clays in general. 
The whole has been brought well up to date. 
The author treats his subject under the following 
heads :—-(1) The origin of clay, (2) chemical pro- 
perties, (3) physical properties, (4) kinds of clay, (5) 
methods of mining and manufacture, (6) distribution 
of clay in the United States, (7) Fuller’s earth. 
The distribution of the clays is considered under 
each State separately, according to the geological age 
of the formations; but an excellent index enables 
references to particular kinds of clay to be found 
readily. ; 
It may be remarked that we are still in the dark as 
to the cause of plasticity in clays, in spite of the 
numerous theories; nor has any generally applicable 
method of measuring this property been discovered. 
Dr. Ries discusses the subject with great fairness. 
We heartily commend his views upon the loose way 
in which kaolin and kaolinite are so often confused, 
and especially his objection to the assumption that 
{kaolinite is the normal basis of all clays; a brief com- 
parison of analyses at once dispels this idea. 
This book is very well produced and free from slips, 
but we are somewhat puzzled by the ‘‘increase in 
texture ’? mentioned on p. 107. 
THE ATIOLOGY OF LEPROSY. 
On Leprosy and Fish Eating. A Statement of Facts 
and Explanations. By Jonathan Hutchinson. 
F.R.C.S., F.R.S. Pp. xxiv+420. (London: Archi- 
bald Constable and Co., Ltd., 1906.) Price 12s. 6d. 
net. 
HE object of this work is stated in the preface 
to be ‘‘to carry conviction to the reader that 
the fundamental cause of the malady known as true 
leprosy is the eating of fish in a state of commencing 
decomposition.’? The various districts in which 
leprosy occurs have been examined, and it is found 
that in practically all fish is consumed as an article of 
diet, often in a more or less stale condition, the 
prevalence of the disease frequently being in a direct 
ratio to the amount of fish eaten. Mr. Hutchinson 
would associate the former prevalence of leprosy in 
the British Isles and in Europe with the Roman 
Catholic ordinances prescribing fish-food on two 
out of every three weel-days, its decline in these 
countries with the relaxation of discipline which pre- 
ceded the Reformation, its extinction with the estab- 
lishment of Protestantism. 
We think that Mr. Hutchinson goes much too far 
in thus ascribing all variations in the prevalence of 
leprosy as being correlated with those of a fish-diet; 
NO. 1948, VOL. 75 | 
even in the fact that the disease is more prevalent 
among men than among women he sees support for 
his hypothesis, for he suggests that women are more 
fastidious feeders than men, that men would be more 
likely than women to obtain fish if this were ex- 
pensive, and so on. Why fish fresh or properly salted 
does not convey the disease and only bad fish does 
is by no means clear, the single suggestion given 
being that there may be some connection between 
tuberculosis and leprosy, and that fish-diet may con- 
tain some constituent which may modify the tubercle 
bacillus and convert it into the leprosy bacillus! Mr. 
Hutchinson maintains that the facts he has collected 
point to the conclusion that the efficient cause of 
leprosy must be some article of food (p. 33), and 
that fish is the only one of universal occurrence which 
can be traced. 
But is it necessary to find a single mode of origin 
for the disease in every part of the world? Surely 
not, and if so there is no need to limit it to fish. 
Mr. Hutchinson admits that personal contact may 
convey the disease, but declares that this mode of 
infection is exceedingly rare, ‘‘where one had acquired 
the disease, hundreds equally exposed to risk had 
escaped ’’ (p. viii). But the latter statement proves 
little; all of us who live in big towns must daily 
come in contact with the virus of tuberculosis, yet 
only an unfortunate few contract the disease. Simi- 
larly, as regards the decline of leprosy, most, if not 
all, infective diseases show periods of epidemic pre- 
valence and of decline; to what can be ascribed the 
disappearance of plague and of malaria from 
England? Mr. Hutchinson says the world-wide dis- 
tribution of leprosy proves that ‘‘it is not solely de- 
pendent upon contagion ’’; this does not appear to 
mean personal contact, but to suggest an origin de 
Would not the same apply almost equally 
to tuberculosis, but would it be said that therefore 
the last-named disease is capable of ‘‘ independent 
origination’’? In the case of tuberculosis, often 
many years may in all probability intervene between 
infection and manifestation; in leprosy we do not 
know how long the virus may lie latent, and there- 
fore an exposure long forgotten may really be the 
determining cause of the attack, without bringing 
in a de novo origin, in those rare cases in which it 
has not been possible to trace the source of infection. 
Lesions of the nasal mucous membrane are ex- 
tremely frequent in lepers, and the nasal discharge 
may therefore be the chief vehicle by which the virus 
is disseminated. It has also recently been reported 
that the mosquito and the bed-bug may harbour the 
bacillus, further channels again by which infection 
may be carried. These, together with the close con- 
tact and promiscuous intercourse which exist between 
the members of native races, seem to us sufficient to 
explain the source of infection in leprosy, fish-diet 
being only a remarkable coincidence. 
In thus criticising Mr. Hutchinson’s theory we do 
not in the least desire to belittle his work, which is 
of the greatest interest, and his bool is a valuable 
contribution to the epidemiology of leprosy. 
nove. 
