ON THE ORIGIN OF DEATH. lOQ 



adult life. There is no old age; there is no death. 

 Clearly, then, since these forms do not die, they may 

 be said to be potentially immortal. The Uving matter 

 of which they are composed passes over without break 

 into a younger generation, and in it life is continued. 

 These facts have long been known, and earlier investi- 

 gators have pointed out the potential immortality which 

 this mode of reproduction implies ; but Weismann was 

 the first to develop this knowledge into a scientific 

 theory which may throw light on other facts. 



When Weismann calls these animals immortal he 

 draws a proper distinction between the terms immortal 

 and eternal. Eternity reaches back into the past as 

 well as out into the future. With eternity he has 

 nothing to do. Neither does he use immortality in 

 the sense in which it is used in theology, — as applied 

 to something which can never die, but must exist 

 throu2:h all future time. His claim is not that the 

 life of a Protozoon is such that it must under any 

 circumstances exist forever, but that it will exist as 

 long as the proper physical conditions exist ; in other 

 words, that death is not inherent in life. 



He compares the life cycle of a Protozoon to the 

 circulation of water which evaporates, gathers in clouds, 

 and falls to the earth only to evaporate again. There 

 is no inherent cause in the physical and chemical 

 properties of water which will bring this cycle to an 

 end. As long as the present physical conditions exist 

 the cycle must continue. So it is, he claims, with the 

 life cycle of a Protozoon ; i.e. division, growth by assimi- 

 lation, division again — and so on without end; there 

 being: no inherent cause in the constitution of the 



