30 BIOLOGY OF DEATH 



general protoplasm for their growth, they also become small in such 

 cells. If this process of the transformation of protoplasm into differentia- 

 tion products continues long enough it necessarily leads to the death of 

 the cell, since the continued life of the cell depends upon the interaction 

 between the general protoplasm and the nucleus. In cells laden with the 

 products of differentiation, the power of regulation is first lost, then the 

 power of division, and finally the power of assimilation; and this is 

 normally followed by the senescence and death of the cells. 



D. Natural death {as distinguished from accidents) 

 occurs normally and necessarily only in animals com- 

 posed of many cells. Unicellular organisms are finally 

 known, to a considerable extent as the result of the bril- 

 liant and painstaking researches of Woodruff and his 

 students, to be immortaL in esse as well as in posse. Since 

 the discovery by Woodruff and Erdman of the process 

 of nuclear reorganization, which they call endomixis, this 

 conclusion is as solidly grounded if we regard a cycle of 

 protozoan divisions as the homologue of the metazoan 

 body, as it is if we consider each individual protozoan as 

 such homologue. Woodruff has been cultivating the com- 

 mon unicellular form Paramecium, shown in Figure 3, 

 for over 13 years. 



During all this time no conjugation or pairing of in- 

 dividuals has occurred. In a recent letter Dr. Woodruff 

 says: "After we had discovered and worked out endo- 

 mixis there seemed no particular use of carefully record- 

 ing the number of generations each day. But the culture 

 is still going on as weU as ever and is at approximately 

 the 8500th generation — 13% years old! On May 1, 

 1915, (just 8 years old) it was at the 5071st generation." 

 If in 8500 generations — a duration of healthy reproduc- 

 tive existence which, if the generation were of the same 

 length as in man would represent roughly a quarter of a 

 million years in absolute time — natural death has not 



