STUDIES ON CLUBROOT OF CRUCIFEROUS PLANTS 



447 



that he received from Mangin were evidently eight or more centimeters 

 in diameter. The writer was unable to procure thionine, the stain that 

 Pinoy used, but he tried both Ziehl's carbol fuchsin and Kuehne's 

 carbol methylene blue, which have always given good results in staining 

 parasitic bacteria in other tissue. Parts of small, slightly swollen roots, 

 as well as pieces of larger roots (of which some were still normal in color 

 and others had begun to turn black), were fixed in Carney's fluid, con- 

 sisting of glacial acetic acid and alcohol. The small, slightly swollen 

 roots after staining showed no signs of bacteria. Pinoy (1905) states 



FlG. 1 10. SAPROPHYTIC ORGANISMS IN DISEASED TISSUE 



A, Partly corroded starch grains between the amoebae, the refractive hila being the only 

 visible part in some of them; B, bacteria in a cell of diseased tissue; C, mycelium of a sapro- 

 phytic fungus in darkened diseased tissue. X 800 



that cocci appear as very refractive bodies among the amoebae. In this 

 experiment, the hila of partly corroded starch grains (fig. no, A) appeared 

 in several instances as spherical, brightly stained bodies; but they could 

 hardly be mistaken for an organism, as the same effect is shown in healthy 

 cells in which entire starch grains may be seen. 



The older, diseased tissue that has not yet turned dark presents a some- 

 what different appearance from that of the youngest swellings. The epi- 

 dermal cells are torn in many places, and rod-shaped bacteria (fig. no, B) 

 are found both within and between the cells. Many of these cells show 

 broken passages in the walls where the organism could easily have entered. 



