1920] 



JONES— MAPLE SEEDS 



137 



percentage variation in the various fractions accompanying des- 

 iccation. 



It can readily be seen that accompanying desiccation under 

 laboratory conditions there is a great increase in F,. One would be 

 led to expect quite the contrary, as condensation is quite commonly 

 associated with desiccation in plants. Table IV shows more in 

 detail to what this increase is due. 



During the period of desiccation there^has been an enormous 

 increase in the percentage of sucrose. Accompanying this increase 



TABLE IV 

 Analysis of fresh and desiccated seeds 



is a corresponding decrease in the starch content. Free reducing 

 sugars remain approximately the same. In the desiccated seeds 

 we also find a slight increase in phosphorus and nitrogen in F 2 . 

 The nitrogen here represents merely the Kjeldahl nitrogen. 



Sugar maple (Acer saccharum Marsh.) 

 Historical 



A very different type of behavior is found when the seeds of 

 the sugar maple are considered. Germination here is initiated by 

 a distinct period of after-ripening. Investigators generally have 

 used the term ''after-ripening" as referring to the series of chemical 

 or physical changes occurring within the embryo or associated 

 structures, which bring to a close the dormant period and make 

 germination possible. The factors operating to cause delayed 

 germination in most types of seed dormancy studied to the present 



