344 A TEXTBOOK OF BOTANY [On. VI, 13 



effective only in skilled hands. Theoretically the best 

 results would be attained when a plant has been stimulated 

 to vigorous vegetative growth until a large reserve of food 

 has accumulated, and then is checked in its stem and leaf 

 growth. . 



Flowers are prone to wilt when cut, even if placed imme- 

 diately in water, because they now lack the root pressure 

 which helped their supply. Moreover, their evaporation 

 current through the cut ducts draws into the latter various 

 micro-organisms which here find such congenial conditions 

 for growth that they fill the passages and stop the water. 

 The devices for preserving the freshness of flowers are ad- 

 justed to neutralize these conditions. Thus, everybody knows 

 that flowers keep best in cool, moist, shaded places, be- 

 cause evaporation is there checked; and florists keep their 

 Roses before sale in refrigerators for this reason. On the 

 other hand, a frequent changing of the water, clipping away 

 the lower and often discolored ends of the stems, the addi- 

 tion of a little salt, dipping the cut ends for a moment in 

 hot water, charring the ends in a flame, all of them devices 

 recommended by different people for preserving particular 

 kinds of flowers, have in one way or another the effect of 

 antagonizing the organic growths in the ducts, thus keeping 

 the passages open. It is said that white flowers last longer 

 after cutting than colored kinds, which perhaps is connected 

 with the fact that they absorb less sunlight than colored 

 kinds, and hence suffer less evaporation from their tissues. 

 Florists have still another device, useful in some cases, de- 

 pending on the fact that since petals usually fall immediately 

 after fertilization, flowers last longer if that is not effected. 

 Fertilization can be prevented by removing the anthers 

 from all flowers as soon as they open. This is commonly 

 practiced with large Lilies. 



