878 



SCIENCE, 



[N. S. Vol. XLIII. No. 1121 



where it depresses functional activity while 

 at the same time enormously stimulating 

 vegetative activity. In the present state of 

 our knowledge no one can say that this is 

 an untenable working hypothesis. Indeed 

 the probabilities in favor of such a view 

 are much stronger to-day than they were 

 five years ago, when I first discovered the 

 cancerous nature of crown gall and began 

 to formulate any ideas. 



12. We might, possibly, concede sarcomas 

 to ,be due to a parasite, but not carcinomas, 

 and certainly not embryomas, yet whoever 

 proposes a parasitic theory of cancer must 

 not only demonstrate his parasite but with 

 it must account for all of these diverse 

 forms, and especially for embryomas, since 

 they are the crux of the whole situation.'' 

 Answer: This is admitted. All of these 

 forms hang together, and the claim is now 

 made that embrj^onal teratomas and gland 

 proliferations can be induced with the same 

 schizomycete previously used to produce 

 sarcomas. As a negation it is of no conse- 

 quence whatever to say that I have only 

 produced them in plants, because, little as 

 it is yet recognized, plants are better 

 adapted than animals to certain purposes 

 of cancer research. In due time and in the 

 same way, let no one doubt, they will also 

 be produced in animals. Whatever else 

 may be denied, the bold fact now stands out 

 demonstrably that all the leading types of 

 cancerous proliferation can be produced in 

 plants with one microorganism. If any one 

 doubts it, let him repeat my experiments. 



13. But this hypothesis of the origin of 

 cancers, and especially of embryonal tera- 

 tomas upsets Cohnheim's theory of "cell- 



3 Gerade in diesem Puiikt scheint mir die interea- 

 santeste und wiehtigste Beziehung der Teratomen 

 zu den anderen Gesehwiilsten zu liegen, dasz wir in 

 den Teratomen eine Gruppe von Produkten vor una 

 haben, in welcher sich die Hauptfragen der 

 Geschwulstlehre wie in eineu Brennpunkt verein- 

 igen (Borst). 



rests." Answer: It does, beyond doubt, 

 very completely. But there is no use of 

 making a fetish of Cohnheim's theory. It 

 is, after all, only a theory. It seemed once 

 to furnish the basis for an explanation of 

 cancer origin, but no one was ever able to 

 build a superstructure on it, for no one can 

 explain why some "cell-rests" grow into 

 cancers while others, and by far the larger 

 number, remain dormant. We shall simply 

 have to write Sic jacet over Cohnheim's 

 theory. It serves well enough for monsters 

 and for typical teratoids, but it does not 

 explain cancers. 



14. Plants are so unlike animals that no 

 comparison can be drawn from diseases of 

 the one group to those of the other group. 

 Answer: On the contrary, fundamentally, 

 plants and animals are very much alike. I 

 mean the resemblances are much more basic 

 than the differences. The latter, very con- 

 spicuous to the eye, may be regarded as 

 differences of degree rather than of kind, 

 corresponding to differences in function. 

 Such an objection could never be raised by 

 a biologist. It shows perhaps better than 

 any other argument how great is the need 

 of injecting biological concepts into cancer 

 research. The cancer problem would have 

 been settled long ago, I believe, had it been 

 approached commonly from this angle 

 rather than from that of pure morphology. 

 Of many of the lower forms of life it is 

 still very difficult to say whether they are 

 plants or animals, of the whole group of 

 bacteria, for example; and for the primi- 

 tive, doubtful forms of life 3''0u will recall 

 that Haeckel created the special kingdom 

 of Protista. To my mind a fundamental 

 unity runs through all living things from 

 the lowest to the highest, like the gold 

 thread through a tapestry ! For one thing, 

 all are alive; all possessed of that unstable 

 equilibrium of forces expressed by the 

 words growth and decay. These phenom- 



