SCOTCH PINE AND 8PRUCE SEED. 763 



the heat of the kiln, and have not been preliminarily heated. 

 Finally, the kind of seed-kiln in use and the manner of 

 conducting the business influences the time required for opening 

 the cones ; if the work proceeds day and night without inter- 

 ruption and the kiln is properly heated, Scotch pine cones 

 require 10 to 12 hours, on the average, before they open. Some- 

 times they require fully 24 hours and under the most favourable 

 conditions eight hours. 



In order to guard against over-heating by the workmen, Keller 

 in Darmstadt has an electric bell in his office communicating 

 with a metallic maximum thermometer in the kiln. 



The cones on removal from the trays are usually thrown on to 

 a grating so that the seeds may be separated from them ; they 

 then always retain a few seeds and in order to secure these, they 

 are placed in a drum-sieve (fig. 835, b), which is made to rotate. 



This consists of a cylinder with wire sides, open at both ends, 

 and there are often projecting bars fastened here and there 

 to its axle inside the cylinder which assist in shaking the cones. 

 It is turned slowly by means of a pulley and belt. The cones 

 are poured into the drum-sieve through a hopper and are so 

 thoroughly shaken within it, as to part with all their seeds. 

 The seeds fall on to the floor and the empty cones pass out at 

 one end of the drum-sieve which is slightly inclined in that 

 direction, through a second funnel, into the store-room for 

 empty cones. 



Seeds of conifers are winged ; it is however preferable to sow 

 them without wings, sowing being then more uniform and the 

 seed better covered with soil, the projecting wings are also more 

 readily seen by birds than the little seeds. The wings must 

 therefore be removed in order to prepare seed for the market. 

 All seeds, however, cannot be completely deprived of their 

 wings, for in many cases the union between seed and whig is so 

 close, that the latter can be only forcibly removed, which may 

 notably reduce the value of the seed. This is the case with 

 silver-fir and larch seed. The wing is not closely united to the 

 seed in Scotch pine and spruce seed and is easily removed 

 (fig. 337). 



Removal of the wings of Scotch pine and spruce seed may be 

 effected in various ways. On a small scale and if it is considered 



