332 CONCLUSION 



they are generally designated as mitochondria, a term given 

 them by Benda, while the whole mass is known as 

 the chondriome. But the chondriome itself is not simple, 

 and in analysing it by means of various strains, Dangard 

 has distinguished, at least among the plants, three categories 

 of cells constituting what he calls the vacuome, the 

 plastidime, 1 and the spherome. These various elements increase 

 in size, change their forms and their manner of grouping, and 

 produce, as Guillermond has shown, various substances. In 

 short they nourish themselves very much in the manner of the 

 beneficent microbes which aid the cell to live instead of 

 destroying it as ordinary microbes do, and they stand in the 

 same relation to the chondriome as the algae, which live in 

 community, or, as we say, in symbiosis, stand in relation to 

 Radiolarians or to Worms of the genus Convolnta. That is what 

 Portier implied when he called them symbiota. We are thus 

 led back by the circuitous route of symbiosis to the question 

 which we previously raised, of the nature of Life. 



The vast horizons which open before us in the future 

 go beyond the old bounds of science. Modern science seeks 

 positive solutions for questions which a short time ago were 

 considered to be outside the domain of observation and 

 experience, and fit only for philosophical speculation. What 

 connexion, for instance, may there be between the motor 

 reactions of Infusoria, simple inevitable reflexes of external 

 stimuli ; the vague and blind sensibility of Sponges and 

 Ccelenterates ; the obscure instinct of Worms ; the remarkably 

 accurate hereditary prescience of the Insect, the free intelligence 

 of the superior animals, and human reason ? How is it that 

 some among so many structural cells have been able to make 

 sensibility their exclusive property, and to concentrate into 

 nervous centres without breaking their co-ordination with 

 all the other cells ; to receive information from them ; to 

 command them by means of a mechanism representing the 

 combined forces of matter, heat, electricity, light, and perhaps 

 other agents between which we now recognize unexpected 

 affinities ? 2 How did thought expand in this environment, 

 and acquire the power to embrace unflinchingly the immensity 

 of the cosmos, to face the enigma of the universe and endeavour 

 to resolve it ? That is the secret of the future. 



1 Comptes rendus de VAcademie des sciences, 1st December, 1919, 9th 

 February and 1st March, 1920. 



2 Cf. the excellent book of Jean Perrin, Les A tomes. 



