374 Chief of a Laboratory of Plant Pathology 



of this disease. You might be interested in knowing that I have well 

 developed specimens of the gall produced by inoculation since I returned 

 to Tucson the 25th of last month. What is more, I have finally run down 

 the organism that causes the disease. It is a myxomycete, something that 

 we have all been looking for for several years. One of the most interesting 

 things regarding it is that it evidently only infests the gall as a plasmodium. 

 Under certain conditions the plasmodium creeps to the surface of the gall 

 and forms amoeba-like bodies which escape into the soil. From my inves- 

 tigations so far, I find two kinds of these amoeboidal bodies, namely, a 

 large one, and another that is very minute. I believe these two forms fuse 

 as they escape from the gall and after a time the resulting amoeboidal mass 

 comes to a resting condition. As yet I do not know the result of this 

 resting condition, but I presume that after a time it breaks up into minute 

 amoeboidal bodies, which, finally reaching other plants, enter them and 

 producing plasmodia and the resulting abnormal tissue. I have traced out 

 the life-history of the organism, with the exception of one or two breaks, 

 which I hope to complete within the course of the next two or three weeks. 



He sent for literature on the myxomycetes and other subject 

 matter which might help him in this study. In his published 

 bulletin, '^'^ he admitted: 



I fully recognize the incompleteness of this investigation and the uncer- 

 tainties regarding certain portions of the work, but, as other duties make 

 it necessary for me to lay aside the work for an indefinite period, I believe 

 it best, on account of the great economic importance of the disease, to 

 publish the results that I have obtained without waiting to make additional 

 spore inoculations or to complete certain cytological investigations which 

 I have in view and hope to make as opportunity permits. 



Crown gall was to be studied by Smith and his laboratory 

 assistants for many years and in many genera and species of 

 plants. He had never planned to devote his laboratory researches 

 to purposes other than investigations in pathology directly or 

 indirectly pertinent to agriculture and the study of plants. But, 

 while studying crown gall, he discerned an analogy between plant 

 teratoid tumors and tumors of animals and man, and, while no 

 complete analogy was ever claimed to be established, he offered 

 his authenticated proofs of resemblances to scientists in the hope 

 of aiding medical research to solve the difficult problem of human 

 cancer. He often consulted pathologists in medical science but 

 at no time claimed to be a medical pathologist. Throughout his 

 career he remained a plant scientist and, by his studies, established 



