190 evolution: the ages and tomorrow 



oyster can and does produce twenty or more million eggs in 

 a single season. One pair can procreate, according to Lull, 

 such numbers of offspring that, if they all survived and mul- 

 tiplied through five generations, their shells would heap up 

 to eight times the size of the earth! L. L. Woodruff once 

 kept an experimental culture of Farmneckim, the slipper an- 

 imalcule, going for many years. In the first five years and 

 starting with one individual (these microscopic animals be- 

 ing able to reproduce by simple fission three times in 48 

 hours), there was potentially brought forth a mass of proto- 

 plasm equal to ten thousand times the volume of the earth. 

 In only a few more years, it has been estimated, the mass of 

 individuals, if all had survived to reproduce, would have ex- 

 ceeded the size of the known universe and would have been 

 reproductively exploding into outer space at the speed of 

 light. Even the elephant which procreates only 4 or 5 young 

 per pair in 50 years of reproductive life could, beginning 

 with a single pair and if all offspring survived to reproduce, 

 cover the plains of Africa with millions of individuals in 

 a few hundred years. 



Of course all the young do not survive to reproduce. In 

 fact, in a more or less stable habitat, where nature has had 

 a chance to strike a balance between the many organisms 

 involved, the total number of living adults remains more or 

 less constant. And this is so in spite of the incredible pow- 

 ers of tgg production. In some fish, for instance, a single 

 pair may produce and fertilize 28,000,000 eggs of which 

 only two will ever become adults, a chance of survival of 

 one in fourteen million. Like the oyster, the fish is highly 

 vulnerable— the eggs are eaten, the young are eaten, multi- 

 tudes are destroyed by bacteria and fungi, the whole habi- 

 tat boils up against them. 



Sometimes an organism is introduced by man or some 

 other agency into a habitat where the death check against 

 it is partially removed, and in these cases we often see a 

 spectacular rise in numbers of individuals in a short time. 



