80 Frincipirs of Plant Culture. 



peratures, as in the honey locust, canna, thorn apple 

 etc. (2T(i). Such seeds, particularly if they have been 

 allowed to become dry, are generally soaked in hot water 

 until swollen, before planting, otherwise thej' might lie 

 in the ground for months and even years l)efore germi- 

 nating. In treating such seeds with liot watei;, unless the 

 temperature at which they swell is known, the water 

 should be heated very gradually until the seeds begin to 

 swell, when it should lie maintained at that temperature 

 until they are fully s\\ollen. It is said that seeds of the 

 honey locust ma> be immeised for a time in boiling water 

 without destroying their vitality, but such treatment is 

 not to be recommended for any seeds. In sieds of this 

 class, 



37. Germination is sometimes Hastened by Cracking or 

 Cutting Away jjart of the Seed-Case. To favdrthe absorp- 

 tion of water, nurserymen otten drill or file a hole 

 through the bony seed-cases of aielurabiuni seeds, or 

 crack dry peach and plum pits in a vise or with an im- 

 plement resembling a nutcrack<'r (27d). 



38. Seeds may Fail to Germinate from a variety of 

 causes, even when exposed to the proper degree of 

 warmth, moisture and oxygen. They may be too old 

 (165), they may not have been suflicientlj' mature when 

 gathered (163), they may have become too dry (169), 

 they may have been subjected to freezing before suffi- 

 ciently dry (167), they may have been stored while 

 damp and thus subjected to undue heating, or they may 

 have been damaged by insects or fungi (321) either be- 

 fore or after maturity. Defects of these kinds are not 

 always visible, hence 



