No. 559] NOTES AND LITERATURE 



435 



conditions, as compared with that dependent upon internal 

 factors. Suspecting that the ultimate death might be due rather 

 to the constancy of the conditions than to anything inherent in 

 the process of living, he set in progress on May 1, 1907, a line 

 derived from a single individual of Paramecium aurclia, keep- 

 ing it under varied conditions. That is, the culture medium was 

 altered from day to day. This line was found to reproduce 

 actively, without degeneration and without conjugation. From 

 time to time Woodruff has published brief papers showing the 

 progress of this line and the relation of the facts to general 

 problems. Such bulletins have been issued at the 465th genera- 

 tion (5) ; then at generations 490 (3), 1,185 (6), 1,238 (7), 1,795 

 (9), 2,121 (10), and 3,029 (22). The culture at last accounts 

 had been in progress five years, during which time the animals 

 had reproduced 3.029 times without conjugation; the potential 

 number of progeny produced being represented by 2 raised to 

 the 3,029th power (a number composed of 912 integers), and 

 constituting a volume of protoplasm equal to 10 1000 times the 

 volume of the earth (22, page 123). Woodruff well concludes: 

 I believe this result proves beyond question thai the protoplasm of a 

 single cell may be self-sufficient to reproduce itself imletimidy. under 



and clearly indicates that senescence and the need of fertilization are 

 not primary attributes of living matter (22. page 123). 



This conclusion lias heen supported by the work of other inves- 

 tigators (notably by that of Enriques), but all will agree that the 

 mainstay of this most important ireneralization is this work of 

 Woodruff. 



Under varied conditions the reproductive power of this line 

 thus showed itself to be indefinitely great. Now arose the ques- 

 tion whether the variation of the conditions was the essential 

 point, or whether the death in a constant hay infusion may not 

 be due to a lack in the hay of elements essential to the prolonged 

 life of the cultures ; in other words, whether it may not be a case 

 of slow starvation. To test this, Woodruff and Baitsell (15) on 

 October 1, 1910. separated from the line living under varied 

 eonditions a set which was kept in a constant medium of 14 per 



