SUMMARY. 89 



will cause premature death. If the seeds are kept in a moist atmos- 

 phere a temperature of even 30 C. (86 F.) will soon cause a marked 

 injury. 



(17) Seeds can endure any degree of drying without injury; that is, 

 by drying in a vacuum over sulphuric acid. It is believed that such 

 a reduction in the water content is necessary if vitality is to be pre- 

 served for a long period of years. However, with such treatment the 

 seed coats become very firm, and there usually follows a retardation 

 in germination as a result of the inability of the seeds to absorb water 

 rapidly enough to bring about the necessary physical and chemical 

 transformations for the earlier stages of germination. 



(18) Seeds that are to be sent to countries having moist climates 

 should be put up in air-tight packages. Experiments have shown 

 that by the judicious use of bottles and paraffined packages seeds can 

 be preserved practically as well in one climate as in another. 



(19) It is of the utmost importance that the seeds be dry before 

 being sealed in bottles or paraffined packages. A drjang of ten days 

 at a temperature of from 30 to 35 C. (86 to 95 F.) will usually be 

 sufficient. However, a better method to follow is to dry until no 

 more moisture is given off at a temperature equivalent to the maxi- 

 mum of the region in which the seeds are to be distributed. If this 

 is not done, the subsequent increase in temperature will liberate an 

 additional quantity of moisture, which being confined in the package 

 will leave the seeds in a humid atmosphere and a rapid deterioration 

 in vitality will follow. 



.(20) Experiments in storing seeds in open and sealed bottles and in 

 packages with definite quantities of moisture and at various known 

 temperatures have shown a very close relationship between the loss in 

 vitality and the increase in water content, the deterioration likewise 

 increasing with the temperature. 



(21) Of a series of experiments the average loss in vitality of seeds 

 kept in envelopes in a "dry room" was 21.19 per cent, "trade condi- 

 tions" 30.63 per cent, "basement" 42.28 per cent, while the loss in 

 the case of seeds stored in bottles was only 8.08, 3.92, and 4.51 per 

 cent, respectively. (See Table XXV.) 



(22) Seeds under ordinary conditions of storage respire quite freely, 

 and respiration is much more rapid if much moisture is present. 

 Within certain limits respiration is directly proportional to the amount 

 of moisture present in the seed and inversely proportional to the 

 duration of vitality. 



(23) Respiration is not necessary to the life of seeds, as they can be 

 kept in conditions unfavorable for respiratory activity and still retain 

 their vitality even better than under normal conditions of storage. 

 Even though respiration be entirely prevented seeds will continue to 

 deteriorate, and sooner or later lose their vitality. 



