134 Principles of Plant Culture. 



dling increases laceration of the cells by the ice crystals 

 within them. 



190. Frost-Injured Plants, Fruits or Roots May often 

 Be Saved from serious damage, if promptly placed 

 under conditions that cause the slowest possible thaw- 

 ing of the tissues, as shading from the sun's rays, im- 

 mersing in ice water or covering with snow. They should 

 ie handled as little and as carefully as possible while 

 frozen. Sprinkling with cold water is often sufficient to 

 restore frost-bitten plants. 



Aside from the death of tender plants by cold, more 

 or less hardy species suffer injury in a variety of ways, 

 of which the following are examples : 



191. Destruction of Terminal Buds by Cold. In 

 plants which do not mature their terminal buds in au- 

 tumn, as the raspberry, sumac, grape, etc., destruction 

 of the tips of growing shoots by frost is a regular oc- 

 currence in climates of severe winters. The distance 

 which the shoots are killed back depends upon the suc- 

 culency of the growth, the severity of the winter and 

 the natural power of the plant to endure cold. Plants 

 thus affected are not always to be regarded as tender, 

 since they often grow wild in climates of very severe 

 winters. 



192. The Darkening of the Wood (Mack-heart) of 

 certain trees, as the pear, in climates of severe winters, 

 appears to be a chemical effect of the cold. It begins 

 at the center of the stem and in extreme cases may ex- 

 tend clear to the cambium, when the bark ceases to 

 adhere, and the tree or branch thus affected dies. In 

 stone fruits, this trouble is often accompanied by a 



