162 
Addresses setting forth the parasitic na- 
ture of the organism have been given be- 
fore this Society by Dr. Townsend, and be- 
fore the Society of American Bacteriol- 
ogists and the American Phytopathological 
Society by myself. I have also twice in 
public addresses before the American As- 
sociation for Cancer Research called at- 
tention to certain general resemblances of 
this disease to malignant human tumors, 
namely, at the Boston meeting in Decem- 
ber, 1909 (lantern-slide address), and 
again in the spring of 1910 at the Wash- 
-ington meeting of the Association, where I 
showed specimens of the disease. The 
whole subject so far as regards the etiology 
of the disease was also summed up in a big 
bulletin published by the Bureau of Plant 
Industry, U.S. Department of Agriculture, 
early in 1911.4 I may assume, therefore, 
that this audience is fairly well acquainted 
with the evidence adduced by us to prove 
the pathogenic nature of the organism we 
have called Bacterium tumefaciens, and 
therefore I shall not spend any time on 
this phase of the subject. Those who are 
not familiar with the evidence can easily 
obtain the necessary publications and if 
these are not convincing they may repeat 
the experiments. 
In a brief way I have also published on 
the newer discoveries upon which I am to 
speak to-day, 2. e., in a third address be- 
fore the American Association for Cancer 
Research,® an abstract of which was pub- 
lished by the Department of Agriculture 
as Circular No. 85, Bureau of Plant Indus- 
try, and in Zeitschrift f. Krebsforschung, 
°'Vide SCIENCE, February 12, 1909, p. 273; ibid., 
August 13, 1909, p. 223; and Phytopathology, 
1911, Vol. I., p. 7. 
*No. 213, ‘‘Crown-Gall of Plants: Its Cause 
and Remedy.’’ ‘To be had from the Superinten- 
dent of Documents, Government Printing Office, 
Washington, D. C. Price 40 cents. 
Buffalo, April 13, 1911. 
SCIENCE 
[N.S. Vou. XXXV. No. 892 
11 Bd., 1 Heft. Since that date the sub- 
ject has been studied continuously. Nu- 
merous sections have been prepared, and I 
will show you lantern slides of photomicro- 
eraphs made from some of these sections, 
so that you will be able to judge for your- 
selves as to the bearing of the evidence. 
It is hardly possible to say who first 
noted the superficial resemblance of over- 
growths on plants to animal tumors. It 
probably goes far back of published ree- 
ords, since we have in English the word 
“‘eanker’’ applied to certain of these over- 
growths, which word is only another form 
of the word cancer. Also in German, the 
word ‘‘Krebs’’ is applied indifferently to 
these overgrowths and to malignant hu- 
man tumors. It is one thing, however, to 
find a superficial resemblance of plant dis- 
eases to animal diseases, and quite another 
to establish any strict analogy. In fact, as 
histological studies on cancer have multi- 
plied animal pathologists have been more 
and more convinced that there is no real 
likeness between the plant overgrowths 
and malignant animal tumors, and this is 
true enough, I believe, for club-root of eab- 
bage, the plant disease most studied in this 
connection. A comparatively recent state- 
ment by Alfred Fischer that the only 
thing they have in common is the name 
(Krebs) may be taken as fairly represent- 
ing the current view.® I shall hope, how- 
ever, to show you before I am through that 
they have a good deal in common, so much, 
in fact, that I believe we have in these par- 
ticular plant overgrowths a key to unlock 
the whole cancer situation. In considera- 
tion of these discoveries many closed doors 
im cancer research must now be opened and 
studies on the etiology of the disease must 
be done over with a view to finding a para- 
site within the cancer cell, and separating 
°Vorlesungen wueber 
1903, p. 277. 
Bacterien, 2te Anuflage, 
