41 



De Caiulolle (1895) investigated the action of repeated 

 freezing on seeds not previously subjected to a special 

 desiccation. The seeds, wrapped in tin foil and enclosed 

 in a sealed metal box, were exposed 118 times to a tem- 

 perature lower than - 100°, the duration of each exposure 

 varying from 8 to 20 hours. No harm was done to ivheat, 

 oats, and fennel by such treatment, but most of the lobelia 

 seeds did not germinate. 



Pictet (1893) mentions exposure of seeds to -200° 

 without injury. 



According to Brown and Escombe (1897), seeds of 12 

 kinds from 8 families, dried in the air, that is, still con- 

 taining 10 to 12% of water, were enclosed in thin glass 

 tubes and put in liquid air for 110 hours. Neither their 

 power of germination nor their growth was impaired in 

 any way. 



In 1899 Moissan presented to the French Academy a 

 note received from Dewar where the latter stated that he 

 had succeeded in solidifying hydrogen and that seeds 

 cooled to the temperature of liquid hydrogen did not lose 

 their germinating power. (C r. Ac. So., 129, 434, 1899). 



Thiselton-Dyer (1899) subjected to the temperature of 

 liquid hydrogen various seeds chosen for their diversified 

 nature (farinaceous or oily), for their various sizes and 

 shapes (ellipsoidal, flattened, etc.). The seeds, simply 

 air dried, enclosed in sealed tubes and cooled tirst in liquid 

 air, were left half an hour in liquid hydrogen (more than 1 

 hour it is said elsewhere in the paper). No change was 

 noticed and germination was normal. In a second series of 

 experiments, the seeds were immersed for 6 hours in 

 liquid hydrogen with which they were directly in contact. 

 No attempt was made this time to graduate the cooling. 

 All the seeds germinated in the normal manner. 



Adams (1905) put in liquid air, for about 24 hours, 6 

 sorts of seeds, some of which were dry, while the others 

 had been buried in the soil for 3 days so as to absorb water. 

 All the dry seeds germinated while none of the moist ones 

 did, except timothy which is known to imbibe water with 



