NATURE 
6o0r 
THURSDAY, AUGUST 15, 1912. 
CANCER PROBLEMS. 
(1) The Cause of Cancer. Being part iii. of 
“Protozoa and Disease.” By J. Jackson Clarke. 
Pp. xi+112+Vviii plates. (London: Bailliére, 
Tindall and Cox, 1912.) Price 7s. 6d. net. 
(2) Preventable Cancer. By Rollo Russell. Pp. 
vii+168. (London: Longmans, Green and Co., 
1912.) Price 4s. 6d. net. 
(3) Further Researches into Induced Cell-Repro- 
duction and Cancer. Vol. ii. Consisting of 
papers by H. C. Ross, J. W. Cropper, and 
E. H. Ross. (The John Howard McFadden 
Researches.) Pp. 125+ix plates. (London: 
John Murray, 1912.) Price 3s. 6d. net. 
(4) The Local Incidence of Cancer. By Charles E. 
Green. Pp. 36; illustrated. (Edinburgh and 
London: W. Green and Sons, 1912.) Price ts. 
net. 
T is impossible at the present time to state 
| definitely that cancer cannot be due to a 
specific micro-organism, but the general arguments 
against this view are so strong that it is difficult 
for anyone making such a claim to obtain a patient 
hearing. Some forms of malignant growth neces- 
sitate the supposition, if a specific parasite be the 
true cause, that the parasite should pick out 
remote, different, and minute groups of cells, 
leaving adjacent and apparently unprotected 
groups untouched. The embryo escapes infection 
from maternal malignant disease of the uterus, and 
the mother is not infected, though the foetus con- 
tained in her body may develop the disease and 
be born with it in an advanced condition. There 
are many other and perhaps more cogent argu- 
ments the enumeration of which cannot be included 
in the space of a short review. 
(1) Dr. J. Jackson Clarke’s book is a further 
plea for his protozoan parasite of cancer. His 
enthusiastic belief in his parasite has apparently 
caused him to overlook the difficulties in the way 
of accepting his view. Certain well-known facts 
connected with malignant growths are quite in- 
compatible with Dr. Clarke’s parasite. Of course, 
it is more than probable that several different 
parasites are indirectly the cause of cancer. The 
spirochete of syphilis as an example is sufficient. 
But this is quite a different thing from a specific 
microorganism for cancer. Advocates of the 
parasitic theory who have a thorough knowledge 
of the class of organisms among which they place 
their parasite may be said to be practically non- 
NO. 2233, VOL. 89] 
existent. Dr. Clarke can scarcely be placed 
among those who have any particular knowledge 
of protozoa, for he treats the existence of Haeckel’s 
monera as being a generally accepted fact, and 
bases arguments upon them which are of funda- 
mental importance to his theory. 
(2) Mr. Rollo Russell, attacking the cancer 
problem from the statistical point of view, comes 
to the conclusion that the disease is largely due to 
feod and drink taken at a high temperature, and 
to the free use of wine, beer, spirits, flesh, coffee, 
tea, and tobacco. The use of statistics may be 
very misleading, and Mr. Russell has made the 
mistake of comparing statistics which are in no 
way comparable. There is also much that sug- 
gests that Mr. Russell’s facts are in other respects 
not sufficiently comprehensive or accurate to justify 
his conclusions. For instance, it is important 
to his theory that the lower animals should suffer 
less than man from cancer. He puts forward 
much evidence in support of this view, some of it 
consisting of actual figures; the rest is merely the 
expression of opinions. 
Mr. Russell concludes that cancer is very 
rare or absent in wild mammals, comparatively 
common in domesticated mammals, and far more 
common in civilised He has omitted 
mice, which animals for some. years past have 
been under observation, almost in millions in 
various laboratories, with the result that cancer 
has been proved to be nearly as common among 
mice as among civilised Perhaps if 
other animals were kept in as large numbers 
and under as careful observation, it would be 
proved that the frequency of cancer did not 
vary in the manner suggested by the particular 
figures and opinions collected by Mr. Russell. 
Again, Mr. Russell says that the stomach is the 
commonest site of cancer in man, the liver being 
next. This is not so. Primary cancer of the 
liver, which is evidently implied, is very rare. 
There are probably several causes of cancer. Diet 
may be among them, but Mr. Russell has not 
proved this. 
(3) The previous publications by Mr. H. C. Ross 
and his collaborators relating to “Induced Cell 
Reproduction and Cancer” have already been 
noticed in these pages. The present excursion 
into the unknown inspires no more confidence than 
those which preceded it. The accuracy of the 
observations now described depends upon the 
accuracy of those described before, and they in 
turn depend upon the accuracy of an equation in 
which degrees of temperature, minutes of time, 
cubic centimetres of solutions are added 
It is difficult after such a beginning to 
B B 
man. 
men. 
and 
together. 
