220 University of California Puhlications in Botany [Vol. 5 



(4) Six, seven, and eight-year-old tobacco seed was found 

 to give relatively high percentage of total germination in most 

 cases. 



(5) Eapidity of germination in general was found to be 

 independent of the age of the seed and to be characteristio of 

 the seed of certain species or varieties throughout and not char- 

 acteristic of others. 



(6) A certain period of "after ripening" seemed to be essen- 

 tial for average germination percentages as shown in the case 

 of 1912 N. acuminata-\Siv\ei\e^. Seed taken from dehiscing 

 capsules on the plants in the field gave very low percentages of 

 germination in the case of N. acuminata-varieties alone. 



(7) Fi hybrid seed three years old gave higher percentages 

 of germination than the seed of the parents of the corresponding 

 cross and of the same age. 



(8) The relation between the germination of parent and 

 hybrid seed indicate that interesting and possibly important sup- 

 plementary results can be obtained by the germination under 

 controlled conditions of the seed used in hybridization experi- 

 ments. 



VIII. DISCUSSION OF RESULTS 



The preliminary nature of this communication makes un- 

 necessary any detailed discussion of the results obtained. 

 Throughout mention has been made of further germination tests 

 at present in progress or contemplated which are designed to 

 investigate further certain of the more interesting points merely 

 touched upon in the present paper. 



The real significance of the action of sulfuric acid in hasten- 

 ing or increasing germination opens a field for investigation 

 which should prove important, especially if such treatment is to 

 be included in general agricultural practice. Results at present 

 at hand seem to leave no doubt that in the case of N. acuminata- 

 varieties at least the action of sulfuric acid is not restricted to 

 weakening the hard outer coverings of the seeds so that water 

 can penetrate more rapidly or that the germinating seed can 

 break them more easily, but that its action is further strikingly 

 effective in increasing the rate of growth during at least the first 

 three months of the plant's life. 



