464 THE WONDER OF LIFE 



manent buds, so some animals remain always young. 

 In what is called paedogenesis, sometimes illustrated by 

 the Axolotl, even the reproduction is shunted back into 

 larval life, so that adult life is reduced to nil. In other 

 cases, the conditions of adult life are extremely riskful, 

 and its duration is contracted to a few weeks or days or 

 even hours ! In other cases, it is the larval life that is 

 condensed ; thus in the freshwater crayfish, what comes 

 out of the egg is practically a miniature adult ; all the 

 usual larval stages, so characteristic of higher crustaceans, 

 have been telescoped into the embryonic development with- 

 in the egg. Or it may be that the larval life is drawn out 

 for years. The idea should be linked on to what has been 

 noted in regard to the successive chapters in the routine of 

 parental behaviour (see p. 430). It is, in a word, the idea of 

 temporal variations, that the life-histories of animals are 

 like tunes, which may be much altered by playing one part 

 out of all proportion slowly, and another part very quickly. 

 We may even go further, and recognize that there are 

 youthful types of organisms and others which are born old. 

 But this is the beginning of another story. 



The Story of Niners. A score of miles, as the crow 

 flies, from the sea, there is a stretch of slowly -flowing river, 

 from which a mill-race has borrowed most of the water. 

 There are many pools with sand or mud, and if this be 

 stirred, we get a glimpse of curious, sluggish, eel-like crea- 

 tures, variously known as niners, or prides, or larval 

 lampreys. Some four to six inches long at the end of their 

 fluviatile life, with a polished dark skin, with a horse-shoe 

 lip around a toothless mouth, they are jawless, limbless, 

 and scaleless, and therefore cannot be ranked as fishes. 

 Although they are called ' niners ' ? i.e. nine-eyes (German, 



