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Scientific Proceedings (94). 



be true malignant tumors. They dwarf the inoculated plant. 

 The parts of the inoculated stem become necrotic above and 

 even below the point of inoculation. Microscopically the galls 

 show invasion and destruction of the neighboring normal tissues. 

 In accordance with the findings of Smith a number of crown galls 

 were obtained containing leafy shoots. Smith considers the latter 

 condition to be analogous to human embryomata. A close micro- 

 scopical study of the crown gall revealed characteristics which 

 differ materially from the conditions obtained in animal cancer. 

 In the majority of the specimens investigated the entire gall 

 presents a uniform morphological appearance of small, young, 

 undifferentiated cells. In other tumors the central growing part 

 presents the usual appearance of a crown gall, while the periphery 

 shows the development of adult differentiated tissue (parenchyma) . 

 This parenchyma is a part of the new growth and not of the normal 

 tissues of the inoculated plant. The same is true of rudimentary 

 organs (conducting system) or even a whole rudimentary organ- 

 ism (leafy shoot) which may appear at the periphery or in other 

 parts of the ordinary crown gall. Such an appearance of highly 

 differentiated tissues subsequently to and as a part of the de- 

 velopment of a malignant tumor is unknown in animal cancer. 



The conclusion to be arrived at from this study is that a fast 

 developing simple crown gall presents a great deal of analogy to 

 animal cancer and offers an ideal material for the cellular study 

 of the latter condition. On the other hand the structure of the 

 growing central part is identical in practically all the crown galls 

 investigated thus far. It represents therefore only one type in 

 the large group of pathological processes designated under the 

 common name of cancer. It is hardly possible to assert on the 

 basis of the study of the crown gall that all human cancers are 

 formed through the activity of one and the same microorganism. 



