134 THE WONDER OF LIFE 



four lines. The pedigreed culture was maintained by 

 taking a specimen practically every day from each of these 

 lines up to May 1, 1912. This facilitated an accurate 

 record of the number of generations attained, and it 

 also precluded the possibility of conjugation taking place, 

 for this process of incipient sexual union does not occur 

 between forms which are all descended from one by 

 repeated asexual fission. 



In the five years there were three thousand and twenty- 

 nine generations, four hundred and fifty-two in the first, 

 six hundred and ninety in the second, six hundred and 

 thirteen in the third, six hundred and twelve in the fourth, 

 and six hundred and sixty-two in the fifth. The mean 

 rate of division was over three divisions in forty- eight 

 hours. 



The slipper-animalcules were as healthy in 1912 as in 

 1907. They had given evidence of the potentiality of 

 producing a volume of protoplasm approximately equal to 

 10,000 times the volume of the earth ! The experiments 

 illustrate admirably the extraordinary self-reproducing 

 capacity of living matter. They also seem to show that 

 given an ideally favourable environment there is no 

 need for the occurrence of conjugation and no reason for 

 senescence. The slipper-animalcules preserve the secret 

 of eternal youth. 



FILLING EVERY NICHE 



Fauna of a Stone. No one who has made the experi- 

 ment will forget the lesson learned by making a census 

 of the population of a single creviced stone brought up by 

 the dredge. Molluscs, Crustaceans, Worms, Echinoderms, 

 Zoophytes, Sponges, Protozoa, and other groups may be 



