Longevity of Cut Flowers. 247 



This blocking may be caused by external factors, or by factors 

 within the plant itself. The most connnon external cause is the 

 development of bacteria in the water surrounding the stem. This 

 is especially likely to happen if flowers are placed in dirty vessels, 

 or vessels, in which the water has been left standing for some time. 

 The bacteria enter the vessels of the stem at the cut end, the sap 

 being an attraction, and after a time form a complete block, pre- 

 venting the ascent of water. This may happen to practically any 

 plant, and the most effectual remedy is to cliange the water fre- 

 quently, and by so doing the accumulation of bacteiia is checked. 



Internal causes of blocking are a gi-eat deal more difficult to 

 •discover and define. There may be ;in exudation of wound gum 

 into the vessels, or the parenchyma cells surrounding tlie vessels 

 may develop outgrowths which push their way into the lumina, 

 and finally form a parenchymatous tissue completely blocking the 

 vessels, and very effectively retarding the ascent of sap. This con- 

 dition is known as tlie formation of a tylosis. 



In order to prevent withering in these cases, it will be necessary 

 to keep the vessels clear, either by preventing the exudation or the 

 abnormal growtii taking place, or by dissolving it as rapidly as it 

 is formed. This will have to be done by placing the stem in some 

 solution which will perform the required action witliout at the 

 same time having any harmful effect on the living tissues of the 

 plant. 



The work was commenced with any plants that happened to be 

 blooming at the time, and various well knoAvn household methods 

 for preserving flowers were tested. Placing the stems in boiling 

 water, removing the bark for some distance up the stems, and char- 

 ring the stems, all proved equally unsuccessful with the flowers 

 used. The only one found to l>e of the slightest use was in the case 

 of dahlias, which, if inclined to droop, would when placed in 

 boiling water, very often completely revive. 



Chrysantliemums and wattles are very inclined to show sudden 

 abnormal droojiing, and in one or two cases this Avas proved to be 

 due to the present of masses of bacteria blockins: the vessels, while 

 in others what seemed to be a gununy precipitate could be seen 

 in the vessels by examining a section of the stem. Since the block- 

 ing and consequent withering take place very rapidly, it is most 

 probably caused by an internal secretion of a gummy nature. If 

 this i.s the case it should be able to be prevented by placing the 

 •stems, either in a solution which will cause a precipitation on the 



