34 



THE JOURNAL OF BOTANY 



From the base of this cavity a later attack was developed. This, 

 with other characters, clearly established that it was the mysterious 

 disease we were dealing with. Some of the turnips were suffering 

 from Finger and Toe, which was of course quite distinct from the 

 rottenness that was destroying the turnips. 



A careful microscopic examination of leaf and bulb was made, 

 and it was found that the injury was due to bacteria, which had 

 gained access to the living plants between the bases of the young 

 leaves or through the broken surface of the bulb. They were ad- 

 vancing into the substance of the turnip from cell to cell, destroying 

 the tissues as they went. Sections were taken from the diseased 

 parts and examined, and myriads of the bacteria were seen in the 

 cells. They were motile, cylindrical rods, exceedingly minute, the 



Turnip attacked by bacteria. — a, external aspect, showing the crown killed 

 and new growth from the axils of the first leaves, which had naturally fallen 

 off; B, section of the same turnip, showing the crown of the turnip 

 destroyed, the hollow cavity produced by the first stage of the disease, and 

 the further injury by the bacteria in the centre of the turnip. Both half 

 natural size. 



longest about seven times as long as they were broad ; they measure 

 •65 fx in breadth, and from 1- to 4" /x in length. The larger rods 

 multiplied by division into two and four, and thus they varied greatly 

 in length, though not in width. 



Some of the slimy substance from the cavity at the top of the 

 turnip was stained and examined, and was found to be crowded with 

 the same bacteria. Cultures were tried in a mixture of gelatine and 

 turnip decoction by introducing into the mixture the bacteria taken 

 from different parts of the diseased swedes, the medium and in- 

 struments being carefully sterilized ; and little colonies of very active 



