64 THE MECHANISM OF LIFE 



i.e. by continually repairing the loss of concentration at the 

 centre of the cell. 



The life of the artificial cell may also be prolonged by 

 maintaining around it an appropriate medium. If we 

 prematurely dry such a preparation of artificial cells, the 

 molecular currents will cease, to recur again when we restore 

 the necessary humidity to the preparation. This to my mind 

 gives us a most vivid picture of the conditions of latent life in 

 seeds and many rotifera. 



These artificial cells, like living organisms, have an 

 evolutionary existence. The first stage corresponds to the 

 process of organization, the gelatine representing the blas- 

 tema, and the drop the nucleus. Thus the cell becomes 

 organized, forming its own cytoplasm and its own enveloping 

 membrane. 



The second stage in the life of this artificial cell is the 

 period during which the metabolism of the cell is active 

 and tends to equalize the concentration of the liquid in the 

 cell and in the surrounding medium. 



The third stage is the period of decline. The double 

 molecular current gradually slows down as the difference of 

 concentration decreases between the cell contents and its 

 entourage. When this equality of concentration has become 

 complete the molecular currents cease, the cell has terminated 

 its existence; it is dead. The currents of substance and 

 of energy have ceased to flow — the form only remains. 



These artificial cells are sensible to most of the influences 

 which affect living organisms. Like living cells they are 

 influenced both in their organization and in their development 

 by humidity, dryness, acidity, or alkalinity. They are also 

 greatly affected by the addition of minute quantities of 

 chemical substances either to the gelatinous blastema or to 

 the drops which represent the primary nuclei. We may in 

 this way obtain endless varieties, nuclei which arc opaque or 

 transparent, with or without a nucleolus, and cells containing 

 homogeneous cytoplasm without a nucleus. We may also 

 obtain cells with cytoplasm filling the whole of the cellular 

 cavity or separated from I he cell-membrane. We may obtain 



