SUMMARY. 89 



will ciiiiso preniatiiro doath. If the seeds are kept in a moist atmos- 

 phere a temperature of even 30^ C. {Sd'^' F.) will soon cause a marked 

 injury. 



(IT) Seeds can endure an}' degree of dr3'ini>- without injury; that is, 

 by di'yiii<»' in a vafuum over sulphuric acid. It is believed that such 

 a reduction in the water content is necessar}' if vitalit}' is to be pre- 

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

 seed coats become very firm, and there usualh' follows a retardation 

 in germination as a I'esult 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. 



(is) Seeds that ai'e to be sent to countries having moist climates 

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

 that I)}' the judicious use of bottles and paraffined packag(\s 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 parallined packages. A drying 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 dr}' until no 

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

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

 is not done, the subse([uent increase in temperature will liberate an 

 additional (piantity of moisture, wdiich 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 ver}^ close relationship lietween 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 " drj- room" was 21.19 per cent, "trade condi- 

 tions" 36.63 per cent, "basement" 42.28 percent, while the loss in 

 the case of seeds stored in bottles was only 8.08, 3.92, and 4.5i per 

 cent, respectively. (See Table XXV.) 



(22) Seeds under ordinar}^ conditions of storage respire quite f reel}^, 

 and respiration is nuich 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 })e entirely prevented seeds will continue to 

 deteriorate, and sooner or later lose their vitality. 



