130 THE WONDER OF LIFE 



waited till it became quite dark except for the stars and the 

 steamer lights, and then enjoyed the splendour of oceanic 

 ' phosphorescence '. There is a cascade of sparks at the 

 prow, a stream of sparks all along the water level, a welter 

 of sparks in the wake, and even where the waves break 

 there is fire. So it goes on for miles and hours a lumin- 

 escence due to the rapid vital combustion of pinhead-like 

 creatures (Noctiluca and others), so numerous that a 

 bucketful contains more of them than there are people in 

 London. We are filled with amazement at the prodigal 

 abundance of life. 



Taking the slowest breeder among mammals, Darwin 

 calculated that a pair of elephants, living for over a century 

 and rearing one offspring every ten years, would have in 

 750 years, barring accidents, nineteen millions of descen- 

 dants. Wallace quotes Kerner's statement that a common 

 weed, Sisymbrium sophia, often has three-quarters of a 

 million of seeds, and that if these all grew to maturity and 

 seeded, the whole of the land-surface of the globe would be 

 covered with the result within three years. 



The very general absence of parental care of any sort 

 among fishes is a familiar fact, partly explicable because 

 fishes are creatures of low degree in the Vertebrate alliance, 

 and partly because of the prolific reproduction. With egg- 

 laying in the open water in the great majority of cases, 

 parental care would be difficult, and survival is secured by 

 great reproductivity. It is sometimes extraordinary. A 

 ling weighing 54 pounds had 28,000,000 eggs, a turbot of 

 17 pounds 9,000,000 eggs, a cod of 21 pounds 6,000,000 

 eggs. In four herrings the number of eggs varied from 

 20,000 to 47,000. 



In many of the less differentiated animals there is not 



