162 



Messrs. H. T. Brown and F. Escombe. 



These include representatives of the following natural orders : — 

 Gramineae, Cucurbitaceae, Leguminoseae, Greraniaceee, Compositee, 

 Umbelliferae, Convolvulacese, and Liliaceae. 



Some of the seeds are endospermous, others non-endospermous, 

 and the reserve material consists in some cases of starch, and in 

 others of oil or of mucilage. 



Their germinative power, after being submitted to the low tem- 

 perature, showed no appreciable difference from that of the controls, 

 and the resulting plants, which were in most cases grown to full 

 maturity, were equally healthy in the two cases. 



In 1892 Professor Dewar and Professor McKendrick found that a 

 temperature of —182° C. continued for one hour is insufficient to 

 sterilise putrescent substances such as blood, milk, flesh, &c, and 

 that seeds would germinate after the action of a similar temperature 

 for the same period of time.* 



When we commenced our experiments we were unaware that any 

 other observations of a similar nature had been made, but whilst they 

 were in progress our attention was drawn to an important memoir 

 by C. de Candolle,f in which the latent life of seeds is discussed in 

 the light of a number of low temperature experiments made princi- 

 pally by. himself and R. Pictet, and described at intervals in the 

 Geneva ' Archives.']: In the earlier experiments of C. de Candolle 

 and Pictet, made in 1879, temperatures of -39° C. to -80° C. 

 were employed, and these only from two to six hours, whilst Wart- 

 mann in 1881 exposed seeds for two hours to —110° C. without 

 effect. In 1884 Pictet found that an exposure of various kinds of Bacte- 

 riaceee for three days to —70° C, and afterwards for a further period 

 of thirty-six hours to —120°, did not destroy their vitality, and in the 

 same year Pictet and C. de Candolle exposed seeds to —100° C. for 

 four days with the same result. Pictet, in 1893, further extended 

 his observations to various microbes and also to a large number of 

 seeds, and claims to have cooled them down without effect to nearly 

 — 200° C, but he gives no details of the experiments, nor any 

 indication of the length of time during which the cooling lasted. 

 His conclusions, however, are that, since all chemical action is 

 annihilated at —100° C, life must be a manifestation of natural, laws 

 of the same type as gravitation and weight. 



In his memoir of 1895 (loc. cit.) C. de Candolle discusses very 



* ' Roy. Inst. Proc.,' 1892, vol. 13, p. 699. 



f 'Archives des Sci. Phys. et Nat.,' Geneva, 1895, vol. 33, p. 497. 



% E. Wartman, 1860, ' Archives des Sci. Phys. et Nat.,' 1860, p. 277 ; C. de 

 Candolle and Pictet, 1879, ibid., vol. 2, p. 354 ; ibid., vol. 2, p. 629 ; E. Wart- 

 mann, 1881, ibid., vol. 5, p. 340 ; E. Pictet, 1884, ibid., vol. 11, p. 320 ; R. Pictet 

 and C. de Candolle, ibid., p. 325 ; R. Pictet, 1893, ibid., vol. 30, p. 293 ; C. de- 

 Candolle, 1895, ibid., vol. 33, p. 497. 



