STRATIFYING SEEDS. 



15 



at the top. . In one of these a thermostat (c) is placed, 

 which controls the flow of gas at the jet beneath, and in 

 the other a thermometer (d) may be placed to show the 

 temperature of the water in the jacket." 



3. THE HANDLING AND SOWING OF 

 SEEDS AND SPORES. 



Preparatory Treatijient of Seeds. — Many seeds demand 

 some treatment preparatory to sow- 

 ing. Nearly all hard and bony 

 seeds fail to germinate, or at least 

 germinate very irregularly, if their 

 contents are allowed to become 

 thoroughly dry and hard. The 

 shells must also be softened or 

 broken, in many cases, before the 

 embryo can grow. Nature treats 

 such seeds by keeping them con 

 stantly moist under leaves or mold 

 and by cracking them with frost 

 This suggests the practice known 

 to gardeners as stratification, an 

 operation which consists in mix 

 ing seeds with cartli and e.xpos 

 ing them to frost or to moistuie 

 for a considerable time. 



Stratification is practiced, as a 

 rule, with all nuts, the seeds of forest trees, shrubs, the 

 pips of liaws and often of roses, and in many cases with 

 the seeds of common fruits. Seeds sliould be stratified 

 as soon as possible after they are mature. Small seeds 

 are usually placed in thin layers in a bo.x alternating with 

 an inch or two of sand. Sometimes the seeds are mi.xed 

 indiscriminately in the sand, but unless they are large it 

 is difficult to separate them out at sowing-time. The 

 sand is often sown witli the seed.s, however, Ijut it is 

 difficult in such cases to distribute the seeds evenly, and 



14. sprouting chamber. 



