EFFECTS OF CONJUGATION 73 



becomes loaded with nuclear stuffs which probably renew the 

 supply of material for the production of the various endoen- 

 zymes needed in the vital reactions. 



With the conjugation of Paramecium therefore the ordinary 

 cells are metamorphosed into germ cells with extraordinary 

 activities the protoplasm of the race is completely reorganized 

 by the interchange of nuclear material, the formation of new 

 macronuclei and new micronuclei of a different chemical 

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

 absorption of the old macronucleus and three-quarters of the 

 c-ld 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 

 ii 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, while old age, with natural death is a 

 biological, inevitable, termination of vital activities, and, so 

 far as we know, can only be prevented in the germ cells by 

 fertilization or its equivalent, since epithelial cells, muscle or 

 nerve cells have no possibility of fertilization. 



