336 LIFE AND DEATH. 



escape the necessity of death. They have not, as 

 Weismann remarks, the real immortality of the gods 

 of mythology, who were invulnerable. On the con- 

 trary, they are infinitely vulnerable, fragile, and 

 perishable; myriads die every moment. But their 

 death is not inevitable. They succumb to accidents, 

 never to old age. 



Imagine one of these beings placed in a culture 

 medium favourable to the full exercise of its activities, 

 and, moreover, wide enough in its extent to be un- 

 affected by the infinitely small quantities of material 

 which the animal may take from it or expel into it. 

 Suppose, for example, it is an infusorian in an ocean. 

 In this invariable medium the being lives, increases, 

 and grows continually. When it has reached the 

 limits of a size fixed by its specific law, it divides into 

 two parts, which are indistinguishable the one from 

 the other. It leaves one of its halves to colonize in its 

 neighbourhood, and it begins its evolution as before. 

 There is no reason why the fact should not be re- 

 peated indefinitely, since nothing is changed, either 

 in the medium or in the animal. 



To sum up. The phenomena which take place in 

 the cell of the protozoan do not behave as a cause of 

 check. The medium allows the organism to revictual 

 and to discharge itself in such a way and with such 

 perfection that the animal is always living in a regular 

 regime, and, with the exception of its growth and 

 later on of its division, there is nothing changed 

 in it. 



Death a Phenomenon of Adaptation It appeared in 

 the Course of the Ages. This immortality belongs in 

 principle to all the protista which are reproduced by 

 simple and equal division. If it be remarked that 



