Bacteria in their Relation to Vegetable Tissue. 



selected as healthy in all respects, without being able to isolate bac- 

 teria from them. Bacteria, however, were often found in tissue which 

 had been wounded from any cause, and in some cases in such num- 

 bers as to lead one to think that they had possibly multiplied in the 

 plant-tissue. This can happen from the local death of the wounded 

 tissue, which will enable the micro-organisms to gain a foothold, and 

 even though they may not be able to grow within the living plant, 

 they are able to exist for a considerable length of time (as will be shown 

 by the results of artificial inoculation), and thus come to be enclosed 

 in the plant by the healing over of the wounded tissue. This is, I 

 think, a probable explanation of the data recorded by some observers 

 who claim to have actually isolated saprophytic forms from plant- 

 tissues. 1 Lesions so slight as to escape notice, especially in root 

 crops, would allow the access of saprophytic forms to the tissues of the 

 plant, where they might survive for a considerable length of time. 



From the results of my own experiments, the conclusion seems 

 evident that, normally, the healthy plant, with intact outer membranes, 

 is free from bacteria within its tissues. 



In the tabulated results obtained by the artificial inoculation of 

 different bacterial species into vegetable tissue, they will be classified 

 according to their nutritive adaptation. 



TABLE SHOWING ACTION OF SAPROPHYTES IN PLANT TISSUE. 



1 Fazio and others : Revista Internaz. d'Igiene, (1890), I, 3. 



2 Explanation of signs : * denotes presence in moderate numbers. 



** " " " large " 



" absence in culture entirely. 



