RESPIRATION OF SEEDS. 



79 



It is now quite oentM-ally acceptod that respiration is not absolutely 

 necessary for t4ie maintenance of seed life, notwithstanding- i\w fact 

 that (Jray contended that seeds would die of sutlocation if air were 

 excluded." The expei-iuients of Gij^-lioli'' in keepinjr seeds of Jledicago 

 sativa immersed in various liquids for approximately sixteen years, 

 after which many responded to germination tests, has done nuich 

 toward demonstrating the fact that seeds can live for a considerable 

 time in conditions prohil)itino- respiration. 



Kochs*^ succeeded in keeping seeds for many months in the vacuum 

 of a Geissler tube without being able to detect the presence of any 

 carbon dioxid, and conseciuently he concluded that there was no gas 

 o-iven off by intramolecular respiration. 



Romanes'' kept various seeds in vacuum in glass tubes for 16 months 

 and the seeds were not killed. However, his vitality tests can not be 

 considered as entirely satisfactory. In the first place, the number of 

 seeds used (ten) was too small; secondly, the variations in the results, 

 even in the controls, indicate that the samples were not of very good 



quality. 



In the experiments of the writer cabbage and onion seed were kept 

 in a vacuum over sulphuric acid for 182 days. During this time all of 

 the free water had ])een extracted from the seed. When again con- 

 nected with a vacuum gauge the dial showed that there was not the 

 slightest change in pressure, and that consequently no evolution of 

 gases had taken place. The cabbage germinated 75 per cent and the 

 onion 73 per cent as compared with 81 and 74 per cent, respectively, 

 for the controls. 



The results of the various experiments above given demonstrate 

 quite fully that the vitality of seeds, as we connuonly know them, is 

 not interfered with if they are kept in conditions prohibiting respira- 

 tion. Brown and Escombe* hold that all chemical action ceases at 

 temperatures of liquid air. They accordingly conclude that " any 

 considerable internal chemical changes in the protoplasts are rendered 

 impossible at temperatures of —180° to —190° C, and that we must 

 consequently regard the protoplasm in resting seeds as existing in an 

 absolutely inert state, devoid of any trace of metabolic activity and 

 yet conserving the potentiality of life * * * And since at such low 

 temperatures metabolic activity is inconceivable an immortality of the 

 individual protoplasts is conceivable providing that the low tempera- 

 tures be maintained." 



«Amer. Jour, of Sci., 3d series, 24: 297, 1882. 



6 Nature, 52: 544, 1895. 



<;Biol. Centrbl., 10: 673-686, 1890. 



t^Proc. Roy. Soc, 54: 335-337, 1893. 



«Ibid., 62: 160-165, 1897-98. 



