1895.] MICROSCOPICAL JOURNAL. 147 



till the disease had nearly destroyed the root. Then they 

 were less firm, and but slightly wilted. 



In a recently diseased plant the following characters 

 can be made out. The fibro-vascular zone is black, as 

 shown in figure i. This black zone may be traced from 

 the crown, or the vascular region of the leaf, down into 

 the turnip or rutabaga for some distance, frequently for 

 more than half its length. The zone of parenchyma sur- 

 rounding the fibro-vascular bundle in recently affected 

 portions have a more watery appearance. In roots where 

 the disease is much advanced the bark separates from the 

 fleshy portion of the root. When the conditions are favor- 

 able the rot soon affects the whole root and stem. Fre- 

 quently the stem and root become hollow, and contain a 

 disagreeable smelling fluid. In some cases this breaks 

 out as shown in fig. i, page 148 ; or it opens out on the 

 root farther down. In this semi-liquid substance bac- 

 teria of several kinds are found, some having a very 

 active motion. In turnips several different forms were 

 found, most of them bacilli; some of these also exhibited 

 a lively motion. 



HOW THE DISEASE SPREADS. 



In all root-rot diseases with which I am acquainted, the 

 disease spreads from some starting point and extends in 

 all directions, frequently following rows, or circular areas 

 are formed. This disease is no exception to the rule. In 

 one patch the disease made its appearance at one end, 

 spreading in all directions. Frequently a dozen or more 

 plants in a row were affected. In some isolated patches 

 affected rutabagas were found. That this is a disease 

 primarily influenced by the condition of the weather ad- 

 mits of no doubt. As stated before, the disease made 

 great headway in August and early September ; but when 

 the dry weather began, it slowly ceased to spread. Dur- 



