Bacteria in their Relation to Vegetable Tissue. 



29 



about 5-7 cc. of the expressed juice was used. The quantitative 

 results, indicated in the following table, show the influence of the 

 plant j uices upon the growth of different species of micro-organisms. 



Most of the species which were used in the above experiment are 

 those which showed a marked increase when in the plant-tissues for 

 a considerable period of time. This table, however, indicates that 

 the increase began immediately upon the introduction of even small 

 numbers into the cell sap, showing that this fluid possessed no bac- 

 tericidal properties. 



The attempt to test the action of cell sap was also tried in another 

 way. However, this method did not allow of accurate quantitative 

 determination, although the other conditions were more nearly 

 normal. It was based upon the action of root pressure in the plant. 

 Thrifty young plants with good-sized stems, like the Lima bean or 

 geranium, were selected, and after having washed the stems with a 

 disinfecting solution, they were cut off with a sterile knife about an 

 inch from the ground. The stump of the plant was then quickly 

 covered with a short sterile test-tube, which made a moist chamber 

 that prevented evaporation. The pot was then set in a warm place 

 to induce copious root-action, and in 12 to 24 hours a large drop of 

 cell sap had exuded from the cut end of the stem. This clear fluid 

 was then inoculated with a few germs from a fresh culture, to be 

 tested, and after a varying length of time their relative number 

 determined as nearly as possible. 



