88 THE VITALITY AND GERMINATION OF SEEDS. 



(7) The average life of seeds, as of plants, varies greatly with differ- 

 ent families, genera, or species, but there is no relation between the 

 longevity of plants and the viable period of the seeds they bear. The 

 seeds of some plants lose their vitality in a few weeks or months, 

 while others remain viable for a number of years. 



(8) With special precautions and treatment there is no question that 

 the life of seeds may be greatly prolonged beyond that which we know 

 at present, though never for centuries, as is frequently stated. Cases 

 so reported can not be taken as evidence of the longevitj 7 of seeds. 



(9) It is known that seeds retain their vitality much better in some 

 sections of the country than in others. The part which climatic influ- 

 ences play in the vitality of seeds is of much more importance than is 

 generally supposed. 



(10) Experiments have shown that moisture is the chief factor in 

 determining the longevity of seeds as they are commercially handled. 

 Seeds stored in dry climates retain their vitality much better than 

 when stored in places having a humid atmosphere. 



(11) The deleterious action of moisture is greatly augmented if the 

 temperature be increased. Not infrequently is vitality destroyed 

 within a few weeks or months when the seeds are stored in warm, 

 moist climates. If stored in a dry climate, the question of temper- 

 ature within the normal range is of little moment. 



(12) The storage room for seeds as they are ordinarily handled 

 should always be dry. If seeds could be kept dry and at the same 

 time cool, the conditions would be almost ideal for the preservation 

 of vitality; but the difficulties to be overcome in order to secure a dry 

 and cool storage room render this method impracticable. 



(13) The most feasible method for keeping seeds dry and thus insur- 

 ing strong vitality is to store them in well ventilated rooms kept dry 

 by artificial heat. This method of treatment requires that the seeds 

 be well cured and well dried before storing. 



(14) If seeds are not well dried vitality is best preserved at tempera- 

 tures just above freezing, provided that the temperature is maintained 

 uniformly. 



(15) In no case must the temperature of the storage house be 

 increased unless the seed is amply ventilated so that the moisture lib- 

 erated from the seed can be carried off readily by the currents of warm 

 air. If this precaution is not taken the increased humidity of the air 

 confined between the seeds will cause a marked injury. For this same 

 reason seeds kept at low temperatures during the winter will deterior- 

 ate in the warm weather of spring, especially if they contain much 

 moisture. 



(16) Most seeds, if first carefully dried, can withstand long expos- 

 ures to a temperature of 37 C. (98.6 F.) without injury, but long 

 exposures to a temperature of from 39 to 40 C. (102.2 to 104 F.) 



