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PATHOLOGY: E. F. SMITH 
contain totipotent cells, the same results can be obtained, e.g., I have 
obtained on the tobacco a shoot-bearing tumor from the middle of an 
internode, and numerous such tumors from various parts of leaves, 
twenty-seven on a single plant, seven on a single leaf, and too many it 
would seem to be explained on Cohnheim's theory,^ i.e., as growths 
due to the development of embryonic ' cell rests, ' which are conceived 
to be fragments displaced from the embryo in early stages of its growth 
and enclosed in other tissues where they remain dormant until a cancer 
stimulus sets them growing. 
8. Bearing of these discoveries on the cancer problem. — It has been 
pointed out repeatedly that embryomas are the crux of the whole cancer 
problem. Hitherto they have remained unexplained. Now I have 
succeeded in bringing them into correlation with the simpler forms of 
cancer by showing that they also are specific tissue responses to the 
stimulus of a specific schizomycete. If one set of plant tissues is inocu- 
lated sarcoma develops; if another set, carcinoma (?) ; if a third set (and 
this time it must be a complex anlage containing totipotent or nearly 
totipotent cells), an embryoma develops. To a biologist, therefore, the 
conclusion is almost irresistible that human cancer must be due to a 
parasite, and that one parasite may well be the cause of the most diverse 
forms, as we have seen to be the case in plants. Those who consider 
plants and animals so different that no conclusion can be drawn from 
the one to the other will see no interrelation, but I am hoping the 
recorded facts will make a strong appeal to those who know some- 
thing about cell metabolism and the similar response of living plants 
and animals to a great variety of stimuli. 
^See /. Cancer Res., 1, No. 2, April, 1916, and Science, N. S., 43, 871, where I have 
elaborated this idea and also other ideas only touched upon here. 
^Bufeau of Plant Industry, Bulletins No. 213 and No. 255. 
*As this goes to press I have had confirmation of this belief, having received from a 
florist in Massachusetts a crown gall of the rose showing abortive shoots growing out of 
stem tumor. 
*For illustrations of teratomas produced in tobacco leaves by direct bacterial inocula- 
tion consult /. Agric. Res., April 24. 1916, Plate 23. 
