Dec 1921J 
LEVINE — ■ STUDIES ON PLANT CANCERS 
Normal 
Roots Inoculated August 5, Harvested 
October 9, 1920 
Without 
Leaf 
No. 
Total 
Root 
Leaf 
Total 
Gall 
Gall 
Root 
53 
51.50 
46.40 
14.00 
54 
118.40 
64.20 
38.70 
55 
68.70 
40.50 
24.00 
56 
137.60 
103.10 
42.10 
57 
129.00 
73.80 
43.60 
58 
198.60 
123.40 
62.90 
59 
165.50 
90;00 
28.10 
Totals 
1,929.15 
885.65 
1,043-50 
7,339.30 
4,984.45 
2,354.85 
2,459.90 
2,524.55 
Averages . . 
1 1347 
52.09 
61.39 
124.38 
84.31 
39.91 
41.69 
42.78 
Spinks (1913) in his study of water and soil cultures of wheat and barley 
showed that these plants were more susceptible to Puccinia glumanim and 
Erysiphe graminis when the plants were provided with large amounts of 
available nitrogen. Plants which were semi-starved as regards nitrogen 
exhibited a considerable degree of so-called immunity. Peltier (191 8) and 
Peltier and Frederich (1920) showed that in the case of citrus canker the 
hosts were more susceptible when placed in conditions that induced rapid 
and vigorous growth. 
Fromme and Murray (1919), studying the angular leaf spot of tobacco, 
a bacterial disease, found that those factors which promote rapid and 
vigorous growth of the host favor the parasite, and again Thomas (192 1), 
studying the relation of the health of the host Apium graveolens (celery) to 
infection with the fungus Septoria apii, observed that those conditions of 
temperature, feeding, etc., which favored the health of the host as evidenced 
by vigorous development also increased the number of infections on the 
leaves. 
Crown gall is analogous to animal cancer, as maintained by Smith, Levin 
and Levine. In the case of animal cancer, Ewing holds that ''good health 
appears to favor the growth of tumor grafts and poor conditions retard it," 
while Teague claims that he was able to transplant mammary carcinoma 
of dogs only in animals weakened with distemper. In this relation of host 
vigor to virulence of the disease, crown gall, potato wart, club root, and 
other plant diseases resulting in hypertrophy and hyperplasia which have 
not been studied from this point of view are analogous to animal cancer. 
This does not argue for or against the parasitic origin of animal cancer, 
for while the end results in animal and plant cancers are analogous, the 
initial stimuli may be entirely different — parasitic, mechanical, or even 
chemical. 
The correlative of this proposition is quite true also, for Miss Brown 
(1920) has showed that Pestalozzia sp. inoculated into Sapodilla may produce 
