2o6 SCIENCE PROGRESS 



of Penicillium and Botrytis, were also met with. The colonies 

 were confined to the area of the leaf impression, which was 

 distinctly outlined in this way, and no growths appeared on the 

 surrounding medium (see Plate facing p. 204). The organisms 

 were equally abundant on both upper and lower surfaces of the 

 leaf the species apparently varying with the season and the 

 kind of leaf. 



Since this epiphyllous flora is always present upon the 

 surface of green plants, it becomes a matter of considerable 

 interest to determine the part played by the micro-organisms 

 in the ordinary fungoid diseases. Are these bacteria at all 

 concerned in the problem of immunity ? Do they in any way 

 modify the life-histories of other bacteria or fungi with which 

 they come in contact ? I would merely throw out a suggestion 

 that without being in any way harmful germs, they may yet 

 profoundly influence existing conditions in some unsuspected 

 way. 



The question whether non-pathogenic micro-organisms are 

 normally present in plant-tissues and can maintain their ex- 

 istence in the intercellular spaces is another interesting specu- 

 lation. It must be remembered that for the purposes of 

 respiration, etc., the intercellular system of plants is in constant 

 communication with the surrounding atmosphere, and thus an 

 easy entrance is afforded through the stomata or lenticels. 

 Whether having gained an entrance the bacteria can actively 

 live, or persist as spores, in the intercellular spaces requires 

 further elucidation. In 1887 Gallipe's experiments led him to 

 the conclusion that the soil micro-organisms enter the roots or 

 tubers of many plants, and in 1888 Bernheim announced that 

 micro-organisms are to be found in the Indian corn and other 

 cereals. These conclusions have been very adversely criti- 

 cised, and neither Buchner, Lehmann, nor Fernbach and Di 

 Vestea have been able to confirm the results. Lominsky, 

 however, finds that the soil bacteria can pass into the root 

 tissues; and Fernbach and Di Vestea, though considering the 

 interior of healthy, uninjured tissues to be free from bacteria, 

 yet grant the fact of their presence in the interior of cut plants 

 exposed to a damp atmosphere. As far as the evidence goes 

 it indicates a possibility that the intercellular spaces of storage 

 organs in the natural state may harbour living bacteria, but that 

 they would almost certainly be present in detached portions 



