VOLUME LXVII NUMBER 4 



THE 



Botanical Gazette 



APRIL igig 



AFTER-RIPENING AND GERMINATION OF SEEDS 

 OF TILIA, SA:\IBUCUS, AND RUBUS 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 247 



R. C. Rose 



Introduction 



This paper gives the results of an attempt to determine the con- 

 ditions favoring the after-ripening and germination of the seeds of 

 Tilia americana, Sambucus canadensis, and Ruhiis Idaeus, and some 

 of the chemical processes involved therein. Since layering of these 

 seeds usually results in very low percentages of germination, it was 

 thought possible to discover some other means of overcoming their 

 dormancy. 



Literature 



The present state of our knowledge of the causes of delay in 

 germination, and the means of overcoming it, is admirably sum- 

 marized in a recent paper by Crocker (5). He divides seeds which 

 show delay in germination into 7 classes. In 3 of these the seed 

 coats play the important role, while in the fourth dormancy is 

 occasioned by the embryo. Where dormancy or poor germination 

 is due to the seed coat, the use of concentrated sulphuric acid as a 

 carbonizing agent has become a common practice. Rose (23) 

 mentions Rostrup (24) as the first to resort to this treatment, and 



HstS TODARO (25), HiLTNER (12), JaRZYMOWSKI (14), BOLLEY (2), 



and Lo\rE and Leighty (19) as investigators applying the same 

 method. Ewart (9) found this treatment effective with several 



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