1 9 o SCIENCE PROGRESS 



Paramoecia ? So argued Prof. Calkin. Therefore, when the 

 period of decay had arrived and the individuals were dying off 

 rapidly, he tried placing them in various infusions. Vegetable 

 infusions were without effect, but infusions of animal tissues, 

 and particularly beef extract, gave the required result. The 

 rate of growth and of reproduction reached the normal level, 

 and death ceased. Senile decay had given way to artificial 

 rejuvenation. Instead of 170 generations being the limit, by 

 stimulation in the periods of depression Calkin succeeded in 

 carrying a race to the 740th generation, and Woodworth to the 

 860th generation, when the individuals were still healthy and 

 fully active. The living matter of these cells without doubt is 

 potentially immortal ! 



Consider for a moment what incredible chemical activity and 

 stability of character these figures imply. If it was possible to 

 preserve alive all the individuals, then at the 900th generation 

 we should have a number which would need a row of some 

 hundreds of figures to express. The parent cell would have 

 produced the 900th power of 2 individuals like itself. The 

 increase in the bulk of active living matter which would have 

 been formed from non-living had there been space enough and 

 food enough is not less wonderful. At the 350th generation 

 it would have the dimensions of a sphere larger than the 

 known universe! 1 And the surface of the sphere would be 

 growing outwards at the rate of miles a second. Nor is this 

 all, for in addition to the enormous chemical activity implied 

 by a rate of growth which would, if unchecked, produce a mass 

 of living matter larger than the known universe in less than 

 two years, there has been throughout continuous expenditure 

 of energy on incessant and active movement. These animals 

 have been watched continuously for five days, and throughout 

 that time they were ceaselessly moving ! 



The recurring periods of depression show that in the living 

 machine repair is not complete, and that after a time it will, 

 if left to itself, cease working. With the condition of ill-repair 

 there is associated a feature of singular interest. Woodworth 

 specially draws attention to the fact that in the periods of 

 depressed vitality the transmission of characters is imperfect. 

 The moulding power of heredity fails, and many "monsters" 

 are born. 



1 I owe this rough calculation to my friend Mr. Punnett. 



