GERMINATION OF SEEDS. 595 



controls. This experiment is important being the first 

 wholly reliable one ; there can be no reasonable doubt but 

 that the seeds acquired the temperature throughout. More 

 recently Pictet (15) says that he subjected seeds to- 200°C. 

 in liquid air, and that development succeeded as in the con- 

 trols. This statement loses much importance through 

 absence of detail, not even the duration of exposure being 

 given. These experiments are in very important relation 

 to the question of the ' vitality ' of seeds. 



Yet more recently De Candolle (2) gives results of an 

 exposure of 118 days at an average but intermittent tem- 

 perature of - 4 1 '93° C. The species tested were Tritiaun 

 {zmlgarc ?), Avena [satwa f), Foeniciihmi officinale, Mimosa 

 pitdica and Lobelia Eriiuts. Those of each species were 

 enclosed in capsules of tin-foil which were placed in a sheet- 

 iron box, which was completely filled ; the box was soldered 

 and enclosed in a wooden case, that covered all surfaces but 

 one. This was done to preclude injury, for cooling occurred 

 in the refrigerator of a firm of importers of frozen goods. 

 The covering was proved to exert no serious influence on 

 cooling. The cooling agent was cold air. During the 

 experiment refrigeration lasted eight to twenty hours per 

 diem ; the minimal temperature recorded was — 53*89'' C, 

 the maximal — 3778° C. After cooling the temperature 

 assumed that of the recipient ; it is doubtful if this ever 

 reached o°C. Almost all seeds of Triticimi, Avena and 

 Foeniculum germinated normally, but only thirteen out of 

 sixty seeds of Mimosa. Out of a large number of Lobelia- 

 seeds only ten germinated. With Mimosa inhibition was 

 not in all cases due to cold, since many seeds in the con- 

 trols did not germinate ; this could not however be said 

 of Lobelia. This experiment is important on account of 

 its long duration, no similar one having ever before been 

 made. 



Hart^ mentions that seeds planted under shelter of 



glass ashore in Discovery Bay germinated and grew ; 



when the sun was at greatest altitude the temperature 



within the glass was raised one or two degrees, but that 



^Joitr. Bat., 1880, 74. 



