330 BACTERIAL DISEASES OF PLANTS 



Technic. Sometimes there are difficulties in the way of 

 isolating this organism, owing to the occurrence on the cotton 

 plant of yellow saprophytes which somewhat resemble it. These 

 are often found in the spots or on the surface and are perplexing 



FIG. 252. -Bacterium malvacearum: part of an agar-poured plate, enlarged 

 to show fugitive mottling of the surface colonies. From one of the leaf spots 

 shown in Fig. 240. Time, third day. Temperature 23C. Plating of March 

 22, 1915. X 14. 



on the agar-poured plates. For this reason great care should 

 be taken to make the isolations from clean leaves, stems and 

 bolls in early stages of the disease, selecting typical-looking spots 

 which have not yet passed beyond the translucent watery- 



