abstracts: botany 91 



BOTANY. — Crown-gall of plants: Its cause and remedy. Erwin F. 

 Smith, Nellie A. Brown and C. O. Townsend. Bulletin Bureau 

 of Plant Industry, Department of Agriculture, No. 213. Pp. 215, 

 pis. 36. 1911. Crown-gall and sarcoma. Erwin F. Smith. Cir- 

 cular Bureau of Plant Industry No. 85. Pp. 4. June 20, 1911. 



Bulletin 213 deals with a widely distributed and harmful disease of 

 orchard trees and other plants. This disease is commonly known in 

 the United States as crown-gall, but it may occur not only on the crowns 

 of plants, but on roots and shoots. 



The disease has been known for a long time, and under the supposi- 

 tion that it was infectious and injurious various States have made quar- 

 antine laws against it. The disease has been ascribed to various causes, 

 without satisfactory proof, and many persons have been led to believe 

 that it was not due to any organism. The experiments detailed in the 

 Bulletin show clearly that the gall is due to bacteria and is infectious, 

 being readily transmitted not only from plant to plant of the same kind, 

 but also to many plants of widely different families. The Bulletin 

 shows that the growth is not only of itself injurious to the plant, but also 

 may form an open wound through which other parasites are likely to 

 enter, such as the fungus of root rot, and the bacteria which cause blight 

 of apples and pears. 



The Bulletin recommends that the inspection laws now in force in 

 the various States be continued and enforced. It shows what plants it 

 is not advisable to use as a crop following a galled one. It describes the 

 life history and cultural characters of the organism involved; points out 

 the difficulties attending its isolation and identification; gives numerous 

 illustrations showing the nature of the tumors produced and the time 

 involved in their production when pure cultures of the organism were 

 used; shows that the organism has a wide range of host plants, and that 

 the overgrowths produced are in many ways anatomically and otherwise 

 strikingly like those found in certain malignant animal tumors. 



The bacteria causing these plant tumors are not abundant in the 

 tissues, sometimes very rare; are hard to see and difficult to stain; they 

 perish readily both in the tumor and in culture-media; are difficult to 

 cultivate from the tissues unless one knows the technique; do not form 

 abscess cavities after the manner of the tubercle diseases, but multiply 

 in limited number within the tissues and apparently only inside the cells 

 which their presence stimulates into rapid division. The disease forms 

 secondary tumors readily, and on this account is cut out with difficulty. 



