NOVEMBEB 29, 1912] 



SCIENCE 



749 



changes as rapidly as possible. So we con- 

 clude that, disagreeable as it may be, it is the 

 best thing for the science that we should obey 

 the rules of the code. 



CROWN GALL AND CANCER 



Attention should be called again to Dr. E. 

 F. Smith's suggestive paper " The Structure 

 and Development of Crown Gall: A Plant 

 Cancer," ' issued June 29, 1912. In its prepa- 

 ration the author was assisted by Nellie A. 

 Brown and Lucia McCulloch, scientific assist- 

 ants. As expressed by Dr. B. T. Galloway in 

 his letter of transmittal to the Secretary of 

 Agriculture : 



This paper is the result of many months of 

 critical study of hundreds of serial sections pre- 

 pared on the microtome; and so far as relates to 

 the photographic demonstration of the presence 

 of the causal organism within the proliferating 

 cells, to several years of laborious and discour- 

 ■ aging experimentation with a variety of fixing 

 agents and stains. Only recently has it been pos- 

 sible to demonstrate clearly by means of the 

 microscope the presence of the parasitic organism 

 within the cells, although the authors have known 

 for more than five years that this organism must 

 lie located within the cells. 



Proof of the latter contention having been 

 attained the conclusion is reached that 



While it is the rapidly proliferating cancer cells 

 that do the michief they are impelled to behave 

 in this way only because they are under the stim- 

 ulus of a foreign organism which does not destroy 

 them but irritates them to rapid division. 



We can well agree with Dr. Galloway in 

 pronouncing this " a discovery of the first 

 magnitude in pathology." 



The paper is accompanied with one hun- 

 dred and nine " half-tone " reproductions of 

 photographs, often very highly magnified, and 

 these plates constitute the greater part of the 

 evidence upon which the author relies. Among 

 the statements given in the resume the follow- 

 ing may be quoted: 



Crown galls occur on a great variety of plants, 

 but not always on the crown; any part of the 

 root or shoot is liable to attack. 



iBull. 255, Bureau of Plant Industry, U. S. 

 Dept. Agrie. 



Young, well-nourished, rapidly-growing tissues 

 take the disease more readily than old or slow- 

 growing ones. 



They are all of parasitic origin, unless the one 

 on the beet studied by Jensen, Eeinelt and Spisar, 

 in Europe, should prove an exception. 



These galls are due to schizomycetes, either to 

 one polymorphic species, or to several closely 

 related species. Further studies are necessary. 



The parasite has been shown to occur not only 

 in the primary tumor, but also in the secondary 

 tumors and in the connecting tumor strand. 



The tissues of the gall multiply excessively and 

 in opposition to the best interests of the plant. 



The galled tissue, which is often of a soft, 

 fleshy nature, is much subject to decay. It is not 

 usually corked over, and this absence of a pro- 

 tective surface allows the ready entrance of water 

 and of other parasites. 



The tumor originates in meristem, usually in the 

 cambium region. It may perish within a few 

 months or continue to grow (parts of it) for years. 



The tumor consists, or may consist, not only of 

 parenchyma cells but also of vessels and fibers, 

 i. e., it is provided with a stroma which develops 

 gradually as the tumor grows. 



The tumor sends out roots (tumor strands) 

 into the normal tissues. These may extend for 

 some distance from the tumor — how far is not 

 known. These strands consist of meristem capable 

 of originating medullary rays, tracheids and sieve 

 tubes. . 



The stimulus to tUmor development comes from 

 the presence of the parasite within certain of the 

 cells. 



The relation between the host and the parasite 

 may be regarded as a symbiosis in which the para- 

 site has the advantage. 



The bacterium is a soil organism and planters 

 should aim to keep their lands free from it by 

 refusing to plant infected stock. 



The organism is a wound parasite. Its en- 

 trance is favored by careless grafting and by the 

 presence of borers, nematodes, etc. 



Nothing in this bulletin should be construed as 

 indicating that we think the organism causing 

 crown galls is able also to cause human cancer, 

 but only that we believe the latter due to a cell 

 parasite of some sort, and offer the preceding 

 pages in support of this contention. 



Charles E. Bessey 

 tjniveksity of nebraska 



