542 STATE HORTICULTURAL SOCIETY. 



that cucumbers have beeu cultivated for ages, and universally used in a more 

 or less immature condition, and with condiments as a cooling and appetizing 

 dish. For this purpose a cylindrical form, with very slight or no lobing, and 

 a thin, easily removed rind are desirable, while keeping qualities are of little 

 importance. This is the present form and condition of cultivated cucumbers. 



* * Yet that this is not the only form that might have been cultivated is in- 

 dicated by the fact that, even after centuries of cultivation and selection to es- 

 tablish that form, I have each year, in three distinct stocks of long green cu- 

 cumbers, found in about the proportion of one plant to fifty acres, plants all of 

 the fruit of which, though of good size and healthy, were of the shape of the 

 Crookneck squash. In one instance the fruit was not only the shape but had 

 the warty surface, and upon preserving one of them, it dried up within a hard 

 shell, instead of decaying as an ordinary cucumber would. None of these 

 plants showed any other indication of being crosses with the squash than the 

 form. The vine, leaf and flavor of the fruit were distinctly cucumber, and 

 though we have frequently had fields of cucumbers of several varieties near 

 fields of Crookneck squash, I have never seen any increased proportions of 

 Crookneck specimens in the long green cucumbers which are so situated." 



Prof. Tracy also noted several other instances tending in the same direction. 

 Thus several cucumbers were found which approximated the shape of the scal- 

 lop squash, and " also some so near like Jenny Lind muskmelons, that in one 

 instance, the grower insisted it was a melon until it was cut. All of these 

 plants were healthy, and did not seem to be crosses, but simply sports of cu- 

 cumber.'' 



Philosophy of Sap Flow. — Prof. Wm. Trelease in treating of this topic 

 in the New York Tribune said : 



The sap of most plants is taken from the soil by the power of causing 

 osmosis which the roots possess. This force is known to be sufficient to raise 

 the fluid to a hight of over 100 feet unaided, and gives rise to what is gener- 

 ally known as "root pressure." In the stem the fluid passes through the 

 vessels or ducts of the pitted cells of plants which, like the pine, have few 

 vessels. These are all minute tubes in which the sap is supported by capil- 

 lary attraction, so that the root pressure is generally considered to be amply 

 sufficient to force the current to the top of the highest tree. But its motion 

 upward is. induced by the pumping action of the leaves, from which large 

 quantities of water evaporate. 



The ducts and pitted cells through which the stream flows are not entirely 

 filled with sap, but include bubbles of gas with it. As water is withdrawn 

 from the uppermost cells by evaporation, the air in them expands to occupy 

 the additional space, and so exerts less pressure than at first. This allows 

 some of the water lower down to be forced upward into them, by the elas- 

 ticity of the air bubbles in the other cells, the adjustment going on from 

 above downward — the tendency being to equalize the gas pressure through- 

 out the entire plant. While evaporation continues this equilibrium is never 

 reached ; when it stops the balance may be effected and sap remain quiet, 

 unless some disturbing element is introduced. 



The exact balance is probably never reached even when the leaves are off 

 the tree. The sun warms one part of the stem more than another, and the 

 temperature of the whole changes from hour to hour and from day to day. 

 Every change of this sort causes the air within the cell to expand or contract, 



