December 9, 1897] 



NATURE 



139 



pletely arrested for a time or merely temporarily slackened 

 (ralentie), and he gives the results of some new experiments on 

 seeds maintained at from - 37° C. to — 53° C. in the " snow- 

 box " of a refrigerating machine for a period of 1 18 days. Most 

 of the seeds resisted this treatment successfully, and the author 

 concludes that after a sufficient interval of time has elapsed the 

 protoplasm of the ripe seed passes into a state of complete 

 inertness in which it is incapable either of respiration or assimi- 

 lation, and that whilst in this condition it can support, without 

 detriment to its subsequent revival, rapid and considerable lower- 

 ing of temperature. 



De Candolle then points out that if it really be a fact that the 

 suspended life of a resting seed is in any way dependent on 

 respiration we might expect this to be shown by submitting seeds 

 to a barometric vacuum for some time. He does not appear to 

 have followed out this suggestion, and is apparently unaware of 

 the direct experiments on this point carried out by Romanes two 

 years previously ; he argues, however, that if ordinary respira- 

 tion is a factor of any importance, this may be determined by 

 immersing the seeds in mercury for such a length of time as to 

 ensure the complete consumption of the small amount of oxygen 

 contained within their tissues. It was found that when seeds 

 of wheat, and of Lepiditun sativum were thus treated, for periods 

 varying from one to three months, their power of germination 

 was not sensibly affected. 



Although these last described experiments of C. de Candolle 

 go far to show that any considerable amount of respiration is 

 unnecessary for the maintenance of potential life in the proto- 

 plasm of resting seeds, they are not inconsistent with the view 

 that some minute amount of gaseous exchange may be going on 

 during the whole course of the experiment at the expense of the 

 oxygen contained in the seeds at the time of immersion in the 

 mercury. The results would have been far more conclusive on 

 this point if it had been shown that the gaseous oxygen originally 

 contained in the seed tissue had been completely used up in an 

 early stage of the experiment. The experiments of Romanes, 

 however, conducted with high vacua and atmospheres of various 

 gases, leave no room for doubt on this question, and we must 

 consequently abandon all idea of the dormant state of resting 

 seeds having any necessary dependence whatever on ordinary 

 respiratory processes. Neither set of experiments, however, 

 excludes the possibility of molecular interchanges in the proto- 

 plasm itself, such molecular transpositions in fact as those which 

 can often be induced in living cells placed under anaerobic con- 

 ditions, and which are all exothermic in character, and generally, 

 but not necessarily, attended with the liberation of more or less 

 COj. The great value of the low temperature experiments we 

 have described lies in the fact that such processes of autoxida- 

 tion, and in fact any conceivable internal chemical change in the 

 protoplasts, are rendered impossible at temperatures of - 180° C. 

 to - 190° C. , and that we must consequently regard the proto- 

 plasm in resting seeds as existing in an absolutely inert state, 

 devoid of any trace of metabolic activity, and yet conserving the 

 potentiality of life. Such a state has been admirably compared 

 by C. de Candolle with that of an explosive mixture, whose 

 components can only react under determinate conditions of 

 temperature ; as long as these conditions remain unfulfilled the 

 substances can remain in contact with each other for an indefinite 

 period without combining. 



It appears to us that the occurrence of a state of complete 

 chemical inertness in protoplasm, without a necessary de- 

 struction of its potential activity, must necessitate some modi- 

 fication in the current ideas of the nature of life, for this inert 

 state can scarcely be included in Mr. Herbert Spencer's well- 

 known definition, which implies a continuous adjustment of 

 internal to external relations. ^ The definition doubtless holds 

 good for the ordinary kinetic state of protoplasm, but it is not 

 sufficiently comprehensive to include protoplasm in the static 

 condition in which it undoubtedly exists in resting seeds and 

 spores. The definition becomes in fact one of " vital activity " 

 rather than of life. 



1 The following passage from the " First Principles " (Section 25) 

 clearly shows that the author in constructing his definition had not 

 anticipated the possibility of a living organism attaining a state of 

 absolutely stable equilibrium. "All vital actions, considered not separately 

 but in their eiiseinhle, have for their final purpose the balancing of certain 

 outer processes by certain inner processes. There are unce.ising external 

 forces tending to bring the matter of which organic bodies consist into th.it 

 state of stable equilibrium displayed by inorganic bodies ; there are internal 

 forces by which this tendency is constantly antagonised, and the perpetual 

 changes which constitute life may be regarded as incidental to the 

 maintenance of the antagonism." 



NO. 1467, VOL. 57] 



As it is inconceivable that the maintenance of " potential 

 vitality " in seeds during the exposure of more than 100 

 hours to a temperature of - 180° to - 190° C. can be in any 

 way conditioned by, or correlated with, even the feeblest 

 continuance of metabolic activity, it becomes difficult to see 

 why there should be any time-limit to the perfect stability of 

 protoplasm when once it has attained the restmg state, provided 

 the low temperature is maintained ; in other words an im- 

 mortality of the individual protoplasts is conceivable, of quite a 

 different kind from that potentiality for unending life which is 

 manifested by the fission of unicellular organisms, and with 

 which Weismann has rendered us familiar. 



In what manner and to what extent '* resting " protoplasm 

 differs from ordinary protoplasm we do not at present know, 

 but there are indications, notably those afforded by the resting 

 state of desiccated Rotifera, and also by some recent experi- 

 ments of Van Eyck on discontinuous germination ("Ann. 

 Agron," vol. xxi. (1895), P- 236), that ordinary protoplasts 

 may, by suitable treatment, be brought to the "resting" 

 condition. 



In 187 1, Lord Kelvin, in his Presidential Address to the 

 British Association, threw out the suggestion that the origin of 

 life as we know it may have been extra-terrestrial, and due 

 to the "moss-grown fragments from the ruins of another 

 world," which reached the earth as meteorites.^ That such 

 fragments might circulate in the intense cold of space for a 

 perfectly indefinite period without prejudice to their freight of 

 seeds or spores, is almost certain from the facts we know about 

 the maintenance of life by "resting" protoplasm ; the difficulties 

 in the way of accepting such a hypothesis certainly do not lie in 

 this direction. 



We must express our thanks to Mr. Thiselton-Dyer and to 

 Dr. D. H. Scott, for the facilities they have given us in carrj'ing 

 out these experiments in the Jodrell Laboratory. 



Addendum. 



After the completion of the above Note, our attention was 

 called to a recent investigation by M. R. Chodat, on the in- 

 fluence of low temperatures on Mucor mucedo (" Bulletin de 

 I'Herbier Boisier," vol. iv. (1896), p. 894). He found that 

 a lowering of temperature for several hours to -70° to - 110° 

 C. failed to kill young spores of the mucor, and he adduces 

 certain evidence, which is not, however, wholly convincing, 

 that even the mycelium itself, when cultivated on Agar Agar, 

 and whilst in active growth, is able to resist the action of these 

 low temperatures. The author sums up his opinion as to the 

 bearing of his experiments on the nature of life in the following 

 words : — " La respiration elle-meme est evidenmient complete- 

 ment arretee a celte temperature ou les corps chimiques ne 

 reagissent plus les uns sur les autres. Si Ton considere que la 

 vie consiste principalement en un echange continuel de substance, 

 soit par la nutrition intracellulaire, soit par la respiration, alors 

 il faut convenir qu'a ces temperatures basses la vie n'existe plus. 

 C'est une fatale erreur qu'on rencontre dans jiresque tous les 

 traites que la respiration est une condition necessaire de la vie, 

 alors qu'elle n'est qu'une des conditions de sa manifestation. 

 La vie est conditionee par certaines structures. Les forces qui 

 les mettent en jeu peuvent etre des forces toutes physiques. 

 Elles sont simplement les sources d'energie qui pourront mettre 

 la machine en mouvement." 



THE LA W OF CONDENSA TION OF STEAM. 



A T the meeting of the Institution of Civil Engineers on 

 ■^^ Tuesday, November 30, an important paper was read on 

 " The Law of Condensation of Steam," by Prof. Hugh L. 

 Callendar, F.R.S., and John T. Nicolson. 



In the discussion of steam-engine trials it had generally been 

 assumed that the rate of condensation of steam on a surface was 

 practically infinite, so that any surface in direct contact with the 

 steam was immediately heated to the saturation temperature 

 corresponding with the pressure of the steam. It had also been 

 supposed that the amount of condensation under any given 

 conditions was limited, either by the resistance of the film of 

 condensed water to the passage of heat, or by the capacity of the 



1 We find that Prof. Dewar called attention in one of his Royal Institu- 

 tion lectures in 1892 to the bearing of his low temperature experiments with 

 spores, &c., on this suggestion of Lord Kelvin's (see Roy. Inst. Proc, 1892, 

 vol. xiii. p. 699.) 



