FERRuaRY 4, 1904 | , 
OBSERVATIONS ON THE NATURE OF 
CANCEROUS GROWTHS. 
NV ves of the advance made within recent years in 
* our knowledge of the nature of disease can fairly 
be traced to the general recognition of the principle 
that pathological problems can be resolved in the 
first instance into cell problems. Not only is the 
modern practice of aseptic surgery founded on_ this 
principle, but it also forms the basis of rational as 
opposed to merely empirical therapeutics. 
It is not, however, always easy to interpret the evi- 
dence drawn from a study of the cells, for though they 
may be described as the units of bodily organisation 
they are themselves extremely complex. Thus it hap- 
pens that the explanation of this or that series of 
phenomena is often reached by a roundabout route. 
Amongst the diseases in which the cellular aspects 
of the case thrust themselves prominently into the 
foreground, few are perhaps more remarkable than 
those malignant tumours popularly grouped under the 
general term of cancer. These growths are very 
numerous in character, they appear in widely different 
NATURE 3 
regions of the body, and they produce more or less pro- | 
found disturbances in the organism in which they 
occur. They are not restricted to mankind, but, as 
means of investigation are improved, they are shown 
to afflict members of very different groups of animals 
included in the Vertebrata, and it may be expected that 
they will probably be identified in invertebrate animals | 
also when a systematic search is made for them. 
But however diverse these growths may be, both as 
regards the animals in which they occur and in the 
gross structure which they exhibit, they nevertheless | 
present one important feature in common. They all 
essentially consist of cells that are multiplying in a 
manner uncoordinated with the requirements or advan- 
tages of the remaining cells and tissues of the animal 
affected. The growth as a whole behaves as a para- 
site—a foreign organism which lives at the expense 
of, and exercises a destructive influence on, the cells of 
the normal tissues it invades. The growth itself 
also betrays, in a greater or less degree, an organisa- 
tion of its own, and its cells can commonly be readily 
distinguished from those of the host on which it preys. 
This independence on the part of the malignant growth 
has long been recognised, and it is often coupled with 
a power of dispersal in the body that produces 
new centres of infection and consequent spread of the 
disease. This is especially clearly shown in the case 
of a- carcinomatous growth in mice, which can, as 
Jensen has shown, be transferred to the bodies of other 
mice by inoculation, and his results have been abun- 
dantly confirmed by Bashford and Murray in_ this 
country. j 
Although the cellular symptoms are for the most 
part not difficult to recognise, the causes that deter- 
mine the origin of the neoplasm are still to seek. It is 
clear, however, that they operate in producing some 
change in cells that previously were not distinguished 
from those other units of which the body is composed. 
Numerous theories and hypotheses have, from time 
to time, been advanced to account for the phenomena, 
19 
J 
ation has failed to confirm these statements; whilst in 
a number of cases it is certain that normal cell con- 
stituents themselves have been mistaken for the sup- 
posed parasites. A modification of the parasite theory 
| assumes that the organisms are so small as to be be- 
yond the range of microscopic vision, but that the virus 
they produce suffices to provoke that cell-proliferation 
which is so characteristic of the growth. Such a view 
does not appear to advance matters very much, for the 
| supposed virus has not been isolated, nor have the 
organisms credited with its production been procured. 
It may well be that a stimulus of a chemical nature 
underlies the whole process; indeed, it is difficult to 
escape the conviction that it must do so. But the first 
useful stage in the inquiry would seem to consist in the 
obtaining of a definite conception as to the nature of 
the cellular changes themselves. 
A second theory assumes, as its foundation, 
existence of cells that have become displaced, 
have withdrawn from active cooperation in the 
process of building up the organism during the 
early stages of embryonic life. These may be cells 
that should have been destined to give rise to 
the so-called ‘‘ germinal epithelium,’’ or to ordinary 
somatic tissues. In any event, they retain the char- 
acters and properties of embryonic cells, and are ready 
to start into new growth when appropriate conditions 
awaken them from their dormant state. But in 
such circumstances they are, of course, freed from the 
correlating influences that should and would have 
directed and controlled their multiplication. Thus they 
come to exhibit in a marked degree that potential 
independence which is, perhaps, possessed by every unit 
of nucleated protoplasm. 
But this view of the existence of latent germs, scat- 
tered over the body fails to account for the remarkable 
nuclear peculiarities presently to be described, and in- 
deed it seems to savour rather of a petitio principi, 
since it involves the assumption that the very occurrence 
of a malignant (or other) growth necessarily postulates 
the pre-existence of a latent germ at any spot at which 
the disease has made its appearance. 
A third view of the nature of cancer, which may 
perhaps be appropriately designated as the ‘* game- 
toid ’? theory, has quite recently been put forward. 
It is perhaps easily confused with the ‘* embryonic” 
theory just outlined, but in reality it is essentially dif- 
ferent from it. The gametoid theory, whilst taking 
account of the parasitic nature of the growth, is mainly 
founded on the discovery of certain quite peculiar 
nuclear divisions that normally only occur in con- 
nection with the formation of the sexual cells, or of 
their immediate precursors, in the life-history of the 
organism. 
In the first instance it was during an investigation 
into the cytology of anomalous growths of ferns, on 
which the present writer, in conjunction with Mr. 
Moore and Miss L. Digby, was engaged, that certain 
peculiarities, previously noted, by the two observers first 
mentioned, on nuclear divisions in epitheliomata 
the 
or 
| assumed an unexpected significance. .\ renewed inves- 
but it is only when the nature of the altered structure | 
itself is understood that we can expect to be in a posi- 
tion to investigate seriously the nature of the causes 
that produce it, and thence to bring the latter under 
control. 
It has been suggested that a micro-organism is con- 
cerned in the production of some toxin that is more 
directly responsible for the mischief. Sporozoa, yeasts, 
psorosperms, and bacteria, have at different times been 
identified as the exciting causes, but careful examin- 
NO. 1788, VOL. 69| 
tigation of the cytological processes obtaining in 
malignant growths seemed desirable, and this work 
was much facilitated by the additional cooperation of 
Mr. C. E. Walker. 
As the nuclear transformations are somewhat com- 
plicated it may be well to explain more fully the 
relevant facts, such as may be demonstrated in any 
ordinary animal or plant, and then to indicate the 
bearing of these on nuclear divisions characteristic of 
malignant growths. 
When an ordinary cell of the animal or plant is about 
to undergo division, certain definite and constantly 
