Thf. Frost Srip Bhifrhl. 32') 



Prof. Morren asserts : "That no organ whatever is torn by the ac- 

 tion of frost, except in very rare cases when the vesicles of the cellu- 

 lar tissue give way, but that the vesicles of plants arc separated 

 from each other without laceration. 2. That neither the chlorophyll, 

 the nucleus of cells, elementary fiber, amylaceous matter, raphides, 

 nor the various crystals contained in vegetable tissue, undergo any 

 alteration, unless perhaps in the case of amylaceous substances, 

 which, in some cases, are converted into sugar, no doubt in conse- 

 quence of the action of some acid, formed by the decomposition of the 

 organic parts. 3. That the action of frost operates separately upon 

 each individual elementary organ, so that a frozen plant contains 

 as many icicles as there are cavities containing fluid ; the dilata- 

 tion thus produced not being sufficient to burst the sides of the 

 cavities. 4. That such dilatation is principally owing to the sep- 

 aration of the air contained in the water. 5. That this disengage- 

 ment of air from water during the act of congelation, is the most 

 injurious of all the phenomena attendant upon freezing ; introduc- 

 ing gaseous matters into organs not intended to elaborate it, and 

 bringing about the first stage in a decomposition of the sap and 

 the matter it precipitates ; so that a thaw commences a new 

 chemical action destructive of vegetable life. 6. That the expan- 

 sion of the cells and acquiferous organs drives a great quantity 

 of water into the air-cells and air-vessels, so that the apparatus 

 intended to convey liquid only, contains water and air, while that 

 which is naturally a vehicle for air conveys water. Such an in- 

 version of functions must necessarily bedestructive to vegetable 

 life, even if death were not produced in frozen plants by the de- 

 composition of their juices, the loss of their excitability, and the 

 chemical disturbance of all their contents." 



From these statements it would appear tiiat what is termed 

 " frozen sap blight" may be partially remedied in the pear by cul- 

 tivating such varieties as produce firm tissues, and forming plan- 

 tations on dry soil, and uplands secure from standing water on 

 the surface, and a thoroughly drained subsoil. We have seen 

 several thousand pear trees blighted in a single season, compris- 

 ing over a hundred different varieties- The Louise Bonne de Jer- 

 sey was entirely destroyed beyond remedy, while a row of " Ur- 

 banistes" adjoining did not receive the slightest injury. The for- 

 mer having moist tissues, is easily excited ; the latter being u 



