EFFECTS OF CONJUGATION 75 



activities, the protoplasm of the race is completely reorganized 

 by the interchange of nuclear material, by the formation of new 

 macronuclei and new micronuclei of a different chemical 

 make-up, and by the formation of a new cytoplasm through the 

 absorption of the old macronucleus and three-quarters of the 

 old micronucleus. It now contains the potential of a new 

 race of cells, exactly as in the case of a fertilized metazoan egg, 

 and in the race of cells derived from it, some will be germ cells, 

 just as in the case of the metazoan. So far as immortality 

 is concerned, therefore, the unicellular organisms resemble 

 the multicellular; there is a reorganization of the cytoplasm, 

 a new combination of physico-chemical elements, and a new 

 individuality in protozoa, exactly as in metazoa. There is no 

 essential difference in the vital phenomena, only a difference 

 in their manifestations. Old age, followed by natural death, is a 

 biological and inevitable termination of vital activities, which, so 

 far as we know, can only be prevented by fertilization, or 

 by endomixis the equivalent of parthenogenesis, and then 

 only in the germ cells, since epithelial cells, muscle or nerve 

 cells have no possibility of similar reorganization. 



