184 
Journal of Agricultural Research 
Vol. VIII, No. 5 
No unbiased person, it seems to me, remembering that I have, done 
these things with a fleeting stimulus (fluid or vapor) applied entirely from 
a cavity (stomatal, carpellary, or pith) and not acting from within the 
cells as would be the case in cancer, can look at the striking cell prolifera¬ 
tions which I have obtained and which are so like early stages of crown- 
gall without being convinced that the growths would have gone on indefi¬ 
nitely, with the formation of large irregular tumors, rupturing to the sur¬ 
face if the chemical substances leading to the increased osmotic pressure 
could have been applied slowly, continuously, and in varying localities 
as must be the case when the by-products of intracellular proliferating 
bacteria are the cause of the tumor. Moreover, if wood and bark and 
organ fragments of all sorts (18, 21) can be developed out of- place in 
plants by a local stimulus why not also in the same way cartilage, bone, 
muscle, and foetal fragments out of place in animals? 
To conclude, it would seem, therefore, that in local osmotic action 
(possibly in some stages chemical action also) of various substances 
(aldehyde, acetone, alcohol, acids, alkalies) thrown into cells and dif¬ 
fusing from them in various directions, as the result of the metabolism 
of a feeble intracellular parasite or symbiont together with the resultant 
counter movements of water and food supply we have, in crowngall at 
least and presumptively also in animal neoplasms, the explanation of 
tumor growth—that is, of that extensive multiplication of cells in oppo¬ 
sition to physiological control which has so long puzzled pathologists 
and all students of overgrowths. 
SUPPLEMENTARY REPORT OF THE CHEMIST. 
[This report was received too late to be inserted in its proper place in the text. It should be read in con¬ 
nection with the Chemist's Report, on page 169.] 
Flasks N, O, P, and Q, cultures of the hop strain of Bacterium tumefaciens inoculated on November 4, 
and flasks R and S, checks on the hop, were received from Dr. Smith for analysis. 
Flasks N, O, and P were opened on January 15 (72d day), their contents united and distilled to get rid 
of neutral volatile products. This distillate gave a positive test for aldehyde. Alcohol and acetone were 
absent. 
The residue being reduced to about half its original volume was treated with 75 c. c. 5V sulphuric add 
and distilled with steam. The distillate was neutralized with barium hydroxid, evaporated to dryness 
and the crystalline residue dissolved in water and filtered. The filtrate was treated with zinc sulphate. 
This predpitated the barium as sulphate, which was filtered off. The clear filtrate containing the organic 
zinc salts was evaporated to a very small volume and taken up in alcohol. Zinc acetate is soluble in alcohol, 
while zinc formate is insoluble. A considerable predpitate showed the presence of zinc formate. This 
was confirmed by dissolving in water after filtering and boiling with a few drops of silver nitrate, when 
metallic silver was deposited as a mirror. 
The filtrate was evaporated to dryness and taken up in just enough water to dissolve it. On adding 
silver-nitrate solution a brown precipitate formed, which turned black on boiling, indicating formic add. 
Acetic add was not found in these cultures. 
Jan. 16,1917. (Signed.) J. F. Brewster. 
Plates were poured from each one of. these flasks before turning over to 
the chemist and appeared to be pure cultures of the crowngall organism. 
Plants have also been inoculated with subcultures from colonies taken 
from these plates, but it is too early to know results. 
