CAUSE AND NATURE OF CROWN-GALL 49 



EXPLANATION OF PLATE. 



The material from which this plate was drawn was fixed in Flemming's 

 fluid and stained with the triple stain of Safranin, Gentian-violet, and 

 •Orange. (Magnified same as scale ; scale = 10 //.) 



a. A young cell showing the host nucleus greatly enlarged. The cyto- 

 plasm of the cell for the most part has been consumed and the cell lumen 

 filled with the reticulum of the parasite. 



b, t\ and d. Three cells with the host nuclei in various stages of dis- 

 integration, vucuolar and ill-defined, the remainder of the cell lumen 

 filled with the nucleated reticulum of the parasite. 



e. Host cell showing no trace of the nuclear substance, with the excep- 

 tion of the nucleolus, the latter being the last of the nuclear body to be 

 destroyed by the parasite. 



/, g, h, and i. Four infested cells with host nuclei entirely consumed 

 and the cell lumen almost completely filled with the dense reticulum of 

 the parasite, and showing many small bodies surrounded by a hyaline 

 area. These bodies are supposed to be the nucleoli, and the hyaline areas 

 the remainder of the nuclei of the parasite. In h these bodies are mostly 

 in pairs and in one instance appear as a nuclear spindle. 



/. Non-infested cells. 



j, k, and m. Infested cells with contents in form of dark, spherical 

 bodies, some probably oil globules, darkened by the action of the osmic 

 acid, but probably for the most part the reticulum of the parasite broken 

 up into innumerable spheres by action of the fixing fluid. 



//. An infested cell showing large vacuolate, spheroidal bodies, 

 li plasmodes " probably arising from the disorganized protoplasm of the 

 bost cell. 



/. Non-infested parenchyma cells, showing normal nuclei and the 

 small amount of cytoplasmic contents. 



p. A non-infested parenchyma cell with nucleus in process of division. 



r. A cell showing early tracheary tissue, being the origin of a woody 

 nodule. 



o. Normal meristematic tissue. 



