ABSENCE OF DEATH 107 



have been living on since life began. They make good their waste hy 

 continuous and perfect repair. This has been summed uj) in the epi^'ram 

 that death was the price ])aid for a body. 



(2) In the second place, it is a well-known fact that aiiK.ii:/ multi- 

 cellular organisms re{)roduction is attended with loss of lifi/ouc of 

 the simplest — an Orthonectid — dies in giving birth, and the same is 

 true of some worms. Death follows close on the heels of reproduction 

 in the case of animals so different as may-flies, butterflies and lamjjreys. 

 Everyone know^s that llowering and fruiting exhaust the encr-iics of 

 annual plants. In the very morning of life immortality was pawned for 

 love. 



In the Protozoa and Protophytes, however, where the distinction 

 between "body" and reproductive elements has not been diffcretitiaterl, 

 reproduction is a simpler, less expensive process. The Amoeba divides 

 into two, only a metaphysical individuality is lost. There is as little 

 death as when two cells fuse into one, another familiar reproductive 

 phenomenon. Similarly, with spore-formation and budding, we cannot 

 speak of death when there is nothing — not even ashes — left to bury. 

 More prosaically it may be said that the conception of natural death 

 which applies to the multicellular organisms does not apply in the 

 same degree to those which are unicellular. 



Maupas has indeed pointed out that an isolated family of Infusorians, 

 all descended by asexual multiplication from one cell, and therefore 

 not coupling or conjugating with one another, will, after a certain 

 number of generations, come to extinction. But this isolation is hardly 

 a natural condition. Nor, of course, does he deny the violent death of 

 Protozoa. 



(3) Thirdly, it is worthy of note that at least many Protozoa are not 

 subject to death from bacterial i^ifection to the same degree as higher 

 animals. The Amoeba, for instance, seems but little perturbed by the 

 presence of various virulent microbes. It engulfs them and digests 

 them, as the phagocytes of higher animals do when in vigorous health, 

 or when the odds against them are not too strong. 



J, Aethur Thomson, The Science of Life. 



Alternation of Generations 



We have seen that plants and animals produce ascxunlly. 

 and that they also produce sexually, that is to say, they 

 develop into males and females which produce male and 

 female reproductive cells. 



If we consider the Hydrozoa, which usually form colonics 

 of incrusting animals made up of units called zooids rooted to 

 rocks in the sea, we find that they produce asiwualh/, by 

 budding, forms called jelly-fish, or medusae, which are <]uitc 

 unlike the parent that produced them. These jcUy-lish 



