138 



NA TURE 



[December 9 1897 



nearly 400 yards from a 36-fathom sounding, and rather more 

 than a quarter of a mile from one of 130 fathoms. After this 

 the submarine slope, for a considerable depth, is not quite so 

 steep. He also states that, at Funafuti, the vigorous growing 

 portion of the reef appeared to be limited to within about 40 

 feet of the surface. 



It would be premature, as Prof. David remarks, to express an 

 opinion as to the theoretical bearing of these results until the 

 core has been thoroughly studied. But two things seem clear, 

 (i) that true reef has been ])ierced at depths down to more than 

 600 feet, and (2) that throughout the whole of the time repre- 

 .sented lay the mass which has been tested, coral must have 

 grown in great abundance in some part or other of the locality 

 now represented by Funafuti ; for the atoll, it must be remem- 

 bered, is surrounded by water about 2000 fathoms deep, which 

 would completely isolate it from any other coraliferous locality. 



THE VITALITY OF REFRIGERATED SEEDS} 



A CONSIDERABLE difference of opinion still exists 

 ■^*' amongst biologists as to the condition of the protoplasts 

 of resting seeds, spores, &c. , in which all ordinary signs of life 

 may be unrecognisable for a considerable period. 



According to one view, the essential elements of the cell, 

 during the period of inertness, are still undergoing feeble but 

 imperceptible alteration, accompanied by gaseous exchange with 

 the surrounding atmosphere ; and, even when ordinary respira- 

 tion is in abeyance, it is assumed there are small internal 

 changes going on, due to the interaction of certain constituents 

 of the protoplasm, reactions which may be independent of the 

 outside gaseous medium, and which are often referred to under 

 the somewhat vague term of " intramolecular respiration." 



On the other hand, it is sometimes maintained that all 

 metabolism is completely arrested in protoplasm when in the 

 dormant state, and that it then loses, for the time being, all 

 power of internal adjustment to external conditions. 



According to one view, therefore, the machinery of the dor- 

 mant protoplasts is merely "slowed down" to an indefinite 

 extent, whilst according to the other it is completely brought to 

 rest for a time, to be once more set going when external 

 conditions are favourable. 



It appears to us that the advocates of the " slowing-down " 

 hypothesis have scarcely given sufficient attention to the experi- 

 mental evidence available, and that they have been somewhat 

 biassed by a supposed analogy between the dormant state of 

 seeds and the hibernating state in animals, and have also, 

 perhaps, been unconsciously influenced by Mr. Herbert 

 Spencer's well-known definition of life, which implies a 

 constant internal adjustment in the living protoplasm. 



The experiments of the late G. J. Romanes, which were 

 described in a short paper laid before the Society in 1893 {Roy. 

 Soc. Proc, vol. Ivii. p. 335), are full of interest in their 

 bearing on this question. Seeds of various plants were sub- 

 mitted in glass tubes to high vacua of i/ioooocxDof an atmosphere 

 for a period of fifteen months. In some cases, after the seeds 

 had been in vacuo for three months, they were transferred to 

 other tubes charged respectively with oxygen, hydrogen, 

 nitrogen, carbon monoxide, carbon dioxide, hydrogen sulphide, 

 aqueous vapour, and the vapour of ether and chloroform. The 

 results proved that neither a high vacuum, nor subsequent 

 exposure for twelve months to any of the above gases or vapours, 

 exercised much, if any, effect on the subsequent germinative 

 power of the seeds employed. 



These experiments of Romanes are certainly of the highest 

 importance, since the seeds were submitted for a long period to 

 conditions which must certainly have excluded anything like 

 respiration by ordinary gaseous exchange, but the conditions did 

 not preclude with the same certainty the possibility of chemical 

 interactions of some kind or other within the protoplasm, those 

 ill-understood changes, in fact, which have been referred to 

 " intermolecular respiration." It is true that in some of the ex- 

 periments, notably those in which the vapours of chloroform and 

 ether were employed, the probability of any such internal re- 

 actions is rendered somewhat remote ; but still, in most cases, 

 the experiments admit of the possibility of feeble metabolic 

 activity continuing in the cytoplasm. 



1 " Note on the Influenre of very Low Temperatures on the Germinative 

 Power of Seeds." By Horace T. Brown, F.R S,, and F. Escombe, 

 (Read before the Royal Society, November 18.) 



It occurred to us, some months ago, that more evidence would 

 probably be forthcoming on these points if we could submit 

 seeds to a temperature below that at which ordinary chemical 

 reactions take place, thus eliminating any possibility of inter- 

 actions between the constituents of the protoplasm. 



Owing to the kindness of Prof. Dewar, who has been good 

 enough to place the resources of his laboratory at our disposal, 

 and to undertake this part of the work for us, we have been able 

 to ascertain how far the subsequent germinative power of a con- 

 siderable variety of seeds is affected by prolonged exposure to 

 the very low temperatures produced by the slow evaporation of 

 liquid air . 



The seeds, enclosed in thin glass tubes, were slowly cooled, 

 and immersed in a vacuum-jacketed flask containing about two 

 litres of the liquid air, which was kept replenished so as to 

 submit the seeds for no consecutive hours to a temperature of 

 from - 183° C. to - 192° C. About ten litres of liquid air were 

 required for the experiment. 



The seeds had been previously air-dried only, so contained 

 from about 10 to 12 per cent, of natural moisture. After the 

 above treatment they were slowly and carefully thawed, a pro- 

 cess which occupied about fifty hours, and their germinative 

 power was then compared with control experiments made on 

 other portions of the seed which had not been treated in any 

 way. 



The seeds experimented on were as follows : — 



Trigonella fcenum-grcccum. 

 Impatiens balsamina. 

 Helianthus annuus. 

 Heracleum villosiitn. 

 Convolvulus tricolor. 

 Funkia sieboldiana. 



Hordeutn distichon. 

 Avena saliva. 

 Ciicurbita Pepo. 

 Cyclanthera explodens. 

 Lotus Tetragonolobus. 

 Pisum elatius. 



NO. 1467, VOL. 57] 



These include representatives of the following natural 

 orders :— Graminese, Cucurbitaceae, Leguminoseje, Geraniacete, 

 Compositit, Umbelliferae, Convolvulacese, and Liliacese. 



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

 mous, 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 

 temperature, 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 Prof. Dewar and Prof. 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 {Roy. Inst. Proc, 

 1892, vol. xiii. p. 699). 



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 im- 

 portant memoir by C. de CandoUe,^ in which the latent life of 

 seeds is discussed in the light of a number of low temperature 

 experiments made principally 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 Wartmann in 1881 exposed 

 seeds for two hours to - 110° C. without effect. In 1884 Pictet 

 found that an exposure of various kinds of Bacteriaceas 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 ^^'^'^- '^^^•) C- ^^ Candolle discusses very 

 fully whether we must regard the life of the resting seed as com- 



1 Archizies des Sci. Phys. et Nat., Geneva, 1895, vol. xxxiii. p. 497- 



2 E. Wartmann, i860, Archives des Sci. Phys. et Nat., i860, p. 277 ; C. 

 de Candolle and Pictet, 1879, ibiti., vol. ii. p. 354 : ibid., vol. ii. p. 629 ; E. 

 Wartmann, 1881, ibid., vol. v. p. 340 ; R. Pictet. 1884, ibid., vol. xi. p. 320 ; 

 R. Pictet and C. de Candolle, ibid., p. 325 ; R. Pictet, 1893, ibid., vol. xxx. 

 p. 293 ; C. de Candolle, 1895, ibid., vol. xxxiii. p. 497. 



