AvuGUST 5, 1915] 
NATURE 
617 

known that an amylohydrolytic agent, such as a malt- 
extract, is increased in activity by the addition of traces 
of acid sufficient to convert the neutral into the acid 
phosphates. 
I believe that most scientific workers have, like 
myself, a scrap-heap of failures which may repay a 
little digging now and then. In the light of the 
recent discussion in your columns these few potsherds 
which have been recovered from the overlying débris of 
years may at the present moment have something 
more than a mere antiquarian interest. 
Horace T. Brown. 
52 Nevern Square, Kensington, S.W., July 24. 
The Cancer Problem and Radio-activity. 
Pror. JOLY, in an address published in Nature of 
June 10, has given some more facts: in connection 
with the theory associating radio-activity with the 
cause of cancer; and his endeavour to extend the 
theory so as to connect some of the commodities 
which predispose the tissues to the disease will be read 
with interest by those engaged in cancer research. 
But there are other such commodities which Prof. 
Joly has not apparently taken into consideration, 
especially arsenic and manure; and he is not correct 
when the attributes ‘‘sweep’s cancer” to mechanical 
irritation. 
The last point was demonstrated at the recent Home 
Office inquiries on pitch ulceration and cancer, in 
association with which extensive research has been 
made at the John Howard McFadden Laboratories. 
It appears that there are two forms of pitch, the blast- 
furnace variety produced at a lower temperature mostly 
from Scottish coal, and the ordinary gas-tar variety 
made from bituminous coal. Both varieties are similar 
in consistency, and both cause similar mechanical 
injury; yet blast-furnace pitch is harmless, whereas 
gas-tar pitch gives rise to a considerable incidence of 
warts and sweep’s cancer. Coal-dust may cause 
mechanical injury amounting to laceration; yet it 
causes no cancer. Soot, being soft and floury, does 
not mechanically irritate the skin, yet it occasions in 
sweeps more cases of cancer than in any other trade. 
Tar and some of the petroleum fractions are liquids, 
and cannot cause mechanical injury; yet they both are 
sources of skin epithelioma. 
These commodities evidently give rise to the disease 
owing to the presence of some chemical agent con- 
tained in them, for the more they are concentrated the 
more disease do they cause. Coal causes no cancer; 
tar, the residue after the first stage of its distillation, 
causes some cases; pitch, the residue of the distilla- 
tion of tar, causes such an incidence as to necessitate 
two official inquiries; and soot, the last residue of the 
carbonisation of coal, tar, and pitch, causes the most 
cancer among occupied males. The question 1s what 
is the substance that is being concentrated, and how 
does it act? : 
The researches which have been made on this sub- 
ject are based on the fact that many classes of cells 
can be made to divide in response to auxetics—chem- 
ical agents which contain the amidine or amino group- 
ings. This has been shown now with many classes 
of cells, including human cells; and Cropper and Drew 
have recently found that amoebze, when isolated from 
other living organisms and placed in pure water, will 
not divide at all without the addition of an auxetic. 
Auxetics are physiologically set free in a tissue as 
the result of cell-death caused by injury; and when 
they are inoculated into certain tissues can be made 
to give rise to benign tumour formation, both in men 
and animals. There is another group of substances 
(including most of the alkaloids, choline, cadaverine, 
NO. 2388, VOL. 95] 
etc., to some of which Prof. Joly refers) that increase 
the action of auxetics very considerably. They have 
been called augmentors, 
Since auxetics cause benign cell-proliferation—which 
is a very favourable condition for the onset of cancer, 
a large number of the coal-tar commodities and frac- 
tions were tested for auxetics by trying watery extracts 
of them on human cells. The commodities were sent 
to the laboratory by the authorities distinguished by 
numerals only; some were known to cause cancer, 
others were known not to do so; but the workers who 
made the tests were unaware as to which were which 
until the tests were complete. In this way it was 
ascertained that, by the simple test for auxetic or 
augmentor, those commodities (about 20) which give 
rise to cancer can be picked out from a large number 
(about 150) of those which do not. 
Hence it is more than probable that the commodities 
act by virtue of the auxetics or augmentors they con- 
tain; the successive fractional distillations of coal, 
concentrating the auxetic in each stage, causes a 
higher and higher incidence of cancer, until the ulti- 
mate production of soot with the highest incidence 
of all (chimney-sweep’s cancer). 
Since then, all the other commodities which cause 
cancer, such as arsenic, manure, betel nut (a putrid 
mixture of areca and tobacco), tobacco and its smoke, 
“khangri’’ charcoal, some aniline dyes, and _ petrol- 
eum, have been tested, and all contain auxetic or 
augmentor. On the other hand, the harmless blast- 
furnace tar and pitch and the hard Scottish coal 
whence they are derived contain either no auxetic or 
augmentor or only a trace of the former. 
X-rays and radium rays in certain dosage will pro 
duce cancer; but they also cause cell-death, even 
amounting to ulceration, which in its turn sets free 
auxetics resulting in cell-proliferation, which is prone 
to become malignant. Atrophy following nerve 
disease and injury again produces auxetic in a tissue, 
and these atrophic areas are liable to epithelioma, as 
admirably described by Lenthal Cheatle. 
Much work remains to be done, therefore, before 
the theory regarding radio-activity can be proved to 
harmonise with all the facts, which must include an 
explanation of why it causes the death of the patient 
and metastasis. I do not wish to question its sound- 
ness; on the contrary, an experiment which Dr. 
Lazarus-Barlow has kindly made in comparing the 
radio-activity of the auxetic fractions of gas and blast- 
furnace tars appears to be evidence in its favour. 
Even if auxetics ultimately prove to be the sole imme- 
diate cause of cell-division, some physical force must 
produce the division activated by the chemical agent 
when it has arrived within the cell, and it is possible 
that this force is connected with radio-activity. 
In conclusion it may be mentioned that the terms 
“industrial cancer,’ ‘“‘smoker’s cancer,’’ “sweep’s 
cancer,” ‘‘arsenic cancer,” etc., namely, the diseases 
caused by the commodities mentioned, refer in reality 
only to a predisposition to the disease. The commodi- 
ties themselves do not actually cause cancer; they 
merely render the tissues prone to it, which seems to 
occur in a specific manner. This was clearly shown 
at the inquiries; the commodities always in the first 
instance produce cell-proliferation usually in the nature 
of warty growth; and it is not until an open ulcer 
has appeared, generally at the base of the wart, that 
malignancy supervenes. This fact, coupled with the 
knowledge that augmentors are produced in a _pro- 
liferative site by the action of bacteria, makes one 
suspicious that the exciting cause of cancer is prob- 
ably of bacterial, or, in any case, parasitic origin. 
The clinical evidence and the experiments that have 
been made into the causes of cell-proliferation and 
* industrial cancer demonstrate that when we speak of 


